Andrew Crossley
STAGE 3-5 · 6 WEEKS

MVP development for UK startups

MVP development for UK startups is the work of turning a validated problem into the smallest deployed product that delivers real value to a real user and produces learning you can act on. It is not a prototype and not a demo: it is live, instrumented and someone can pay for it. This service is centred on product scope, one complete user journey, measurement and launch; AI-specific builds have their own dedicated AI app development service.

WHO THIS IS FOR

Where MVP builds go wrong

  • The scope grew from one user journey to four because each addition seemed small.
  • You are three months in with nothing deployed, because everything is nearly ready.
  • You received a large development quote and cannot tell whether the cost is driven by necessary scope, team size or delivery process.
  • You have a beautiful prototype in Figma and no way for a customer to actually use it.
  • Admin panels, settings screens and edge cases got built before the core journey worked.
  • There is no analytics, so launch will teach you nothing beyond whether the servers stayed up.

THE FRAMEWORK

The Crossley Method: idea to first revenue in seven stages

See the full method
  1. STAGE 1DiscoverWeek 1
  2. STAGE 2ValidateWeek 2
  3. STAGE 3PrototypeWeek 3
  4. STAGE 4Build MVPWeeks 3-4
  5. STAGE 5LaunchWeek 5
  6. STAGE 6First RevenueWeek 6
  7. STAGE 7ScaleOngoing

WHAT THE WORK COVERS

MVP development across stages three to five

This service assumes the problem is validated. If it is not, start with product validation — building first is the most expensive way to discover nobody wanted it.

Prototype

The core journey is made clickable and tested with representative target users before production code expands. It is cheap to change at this point, which is exactly why the flow should be challenged here.

Build MVP

One journey, built and deployed continuously with AI tooling where useful. Auth, data, the core loop and nothing else. Everything not on the critical path is deliberately deferred.

Instrument

Analytics and an activation funnel from the start. Where AI features exist, an evaluation set is added so quality can be measured rather than guessed.

Launch

Landing page, pricing, onboarding and a payment or waitlist path, so the product can convert rather than just exist.

HOW IT RUNS

The six-week build

  1. Week 1

    Scope and prototype

    Define the single journey. Build a clickable prototype and test it with target users. The hardest work of the project is deciding what is not in it.

  2. Week 2

    Foundations

    Data model, auth, deployment pipeline and the first thin slice of the core journey live on a real URL. Deployed from day one, never local-only.

  3. Weeks 3-4

    Core build

    Frequent deploys. The journey working end to end, including AI components with evaluation attached where relevant.

  4. Week 5

    Launch surface

    Landing page, pricing, onboarding sequence, analytics, and payment or waitlist depending on your model.

  5. Week 6

    Launch and handover

    Public or controlled launch, first-user evidence, full code and infrastructure handover, and a next-six-weeks roadmap based on what the initial usage shows.

PRICING

My MVP development pricing

These are my current fixed-scope service prices, not market-wide benchmarks. Scope changes are priced separately rather than hidden inside an expanding project.

Prototype only

£3,000

One week. Clickable prototype of the core journey, tested with target users. Enough to challenge the flow and make a better-informed build or no-build decision.

Six-week MVP

£12,000-£25,000

Validated idea to launched product: build, launch surface, analytics and handover. The range depends on integrations, product complexity and any AI evaluation requirements.

Build with your team

£4,000-£8,000/mo

You have engineers; I bring the product leadership and AI-accelerated build practice. Ongoing, one to two days a week.

Building rather than hiring? Get a number in 60 seconds with the MVP cost calculator.

COMPARISON

Product-leader-led build vs a development agency

Both models can be the right choice. The useful comparison is what uncertainty you are buying help with: deciding what the MVP should be, or adding implementation capacity for a scope that is already well defined.

FactorProduct-leader-led buildDevelopment agency
Commercial modelMy fixed-scope MVP is £12,000-£25,000Project price varies with scope, team size, specialisms and delivery model
TimelineMy focused build is planned around a six-week delivery windowDepends on scope, team structure, dependencies and approval cycles
Scope decisionsActively cut, because scope is the main product riskUsually governed by the agreed project scope and change process
Who you deal withOne product lead throughoutDepends on the agency structure and may include account, project and delivery specialists
Analytics and evaluationIncluded as part of the product scopeDepends on what is included in the agreed delivery scope
After launchRoadmap based on real usage, with optional ongoing product supportHandover, support and iteration depend on the delivery contract

PROOF

Products and experience behind the approach

Wocal — reported £2.7M pre-money

Founder and CPO from 2020 to 2025. Built and scaled the SaaS platform to 300+ venues, with a reported £2.7M pre-money valuation.

CallFlow AI and Vynl

AI and digital product prototypes used to test product scope, user journeys, evaluation and commercial assumptions before adding more surface area.

Co-Ride

Community carpooling platform at pre-seed stage, with the early product work focused on marketplace liquidity, trust, employer pilots and a narrow core journey.

Just Eat and Sage

Customer, SaaS and marketplace experience that informs how I think about adoption, operational reality, retention and commercial outcomes after launch.

From app prototype to working MVP

Most founders arrive with an app prototype rather than an idea. It might be a Figma flow, a clickable mock, or an AI app prototype generated in Lovable, Bolt or Cursor over a weekend. The prototype has already done its job: it made the concept tangible enough to test. What it cannot do on its own is show how a real customer behaves through a real task with real data.

The route from a prototype to a working MVP is narrower than people expect. You keep one journey and delete the rest. You replace demo data with the messy inputs you will actually receive. You wire authentication and data access properly. You attach analytics and, where the product uses AI, an evaluation set so quality is measurable rather than felt. Then you add pricing and a payment or waitlist path, so launch produces a commercial answer.

If your product is specifically AI-first — an assistant, RAG product, voice workflow, agent, matching product or AI feature inside SaaS — use the dedicated AI app development service at /idea-to-mvp. This page owns the broader MVP Development UK intent for startups regardless of whether AI is part of the product.

  • Prototype: simulates the journey, often with demo data, before customers can genuinely rely on it.
  • MVP: deployed, real data, real accounts, instrumented, with a real conversion or payment path.
  • Keep one journey from the prototype and defer everything else deliberately.
  • Model infrastructure and any AI usage cost per user before scale, not after.
  • Estimate the spend first with the MVP cost calculator at /mvp-cost-calculator.
  • AI-first product? Use /idea-to-mvp for AI App Development UK.

The scoping decision that determines everything

An MVP has one job: get a real user through one valuable journey and learn from it. Every feature that is not on that journey is a delay to learning, and delayed learning is the main risk at this stage.

The practical test I use is simple. Write down the single sentence describing what a user does and what they get. Anything that does not directly enable that sentence goes on a list for later. Admin panels, settings, team management, onboarding wizards and notification preferences can often wait until real usage shows they matter.

This is difficult because every deferred item has an advocate and each one individually seems small. The compounding is what creates the delay: several small additions can turn a focused MVP into a much larger product before the core assumption has been tested.

How AI tooling changes MVP delivery

AI-assisted build tools can reduce the time spent on boilerplate, first-pass interfaces and repetitive implementation. Tools such as Lovable, Cursor and Claude Code can turn a well-specified screen or workflow into working code quickly enough to change how a small team prototypes and iterates.

What has not changed is everything around the code: deciding what to build, judging whether the output is right, understanding the user and getting someone to pay. Those remain product decisions, and faster implementation makes scope discipline more important rather than less.

The trap is that cheaper building also makes it cheaper to build the wrong thing quickly. The goal is not maximum output; it is the smallest reliable product journey that produces useful evidence.

What ships with every build

  • A live URL early in the build, deployed continuously rather than kept as a local-only demo.
  • The core user journey working end to end for a real, non-technical user.
  • Analytics with an activation funnel defined before launch, not after.
  • Evaluation sets for AI features where they are part of the product.
  • A landing page with real positioning and a working payment or waitlist path.
  • Full ownership: your repository, infrastructure and third-party accounts.
  • A written next-six-weeks roadmap based on what the first usage data shows.

FREQUENTLY ASKED

MVP development questions

How much does MVP development cost?
My current fixed-scope six-week MVP service is £12,000 to £25,000 for a validated idea with one complete journey. That is my service range, not an industry-wide benchmark. The final scope depends on integrations, roles, data complexity and whether AI features require evaluation or specialist handling.
How long does it take to build an MVP?
For my focused service, six weeks is the target delivery window once the problem is validated and the core journey is locked. Broader scope, complex integrations, regulated requirements or unresolved product decisions can extend the work.
What should an MVP include?
One core user journey working end to end, authentication where needed, the data model behind it, analytics with an activation funnel, and a way to convert such as payment or a qualified waitlist. Everything else should earn its place through evidence.
Can you build an MVP without a technical co-founder?
Yes. AI-assisted build tooling can make a credible web MVP possible with a small senior team or product-led build. Engineering depth becomes more important as complexity, scale, integrations and risk increase, but a technical co-founder is not automatically required to test demand or launch a focused first product.
Do I own the code?
Yes. The intended handover is your repository, hosting, database and third-party accounts so the product can continue without a proprietary platform dependency on me.
What is the difference between a prototype and an MVP?
A prototype simulates or demonstrates the experience so you can test the concept. An MVP is deployed, handles real data, and lets a real customer complete the core task so you can measure behaviour.
How do I build an app prototype?
Define the single journey, sketch the few screens it needs, then make it clickable in Figma or use an AI build tool such as Lovable, Bolt or Cursor. Test the journey with real target users before expanding the scope.
Can you turn my AI app prototype into a working product?
Yes. If the prototype is AI-first, the dedicated AI App Development UK page at /idea-to-mvp explains that service in more detail, including evaluation, guardrails, production readiness and launch.
What happens after the MVP launches?
You keep the live product, analytics and code, then use the first real usage to decide the next six weeks. If senior product leadership is still useful after launch, that can move into a fractional CPO or product advisory engagement.
What if my idea is not validated yet?
Start with product validation first. The goal is to gather enough behavioural and customer evidence to justify the build budget or to change direction before that budget is committed.

GET IN TOUCH

Tell me what you want to build

The idea, the user and any evidence you already have. I reply with the next useful step, whether that is validation, a prototype or a scoped MVP build.

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