The verdict in three sentences
A B2B SaaS MVP can be built in 12 weeks in London for 40,000 to 100,000 GBP, with a lean team of one product manager, two developers and one designer. The goal is not a complete product but a version that solves one problem for 10 pilot customers ready to pay or sign a letter of intent. Public support (R&D tax relief, Innovate UK grants, SEIS for investors) can cover 30 to 50% of the bill.
What an MVP costs depending on scope
The budget mainly depends on the number of user roles, external integrations and the security level your first customers expect. Here are three typical profiles seen in 2026 with a London agency (average day rate 650 to 900 GBP).
| MVP profile | Scope | 2026 budget (GBP) | Duration |
|---|---|---|---|
| Light MVP | 1 role, 1 core journey, simple dashboard, Stripe billing | 40,000 to 55,000 | 8 to 10 weeks |
| Standard MVP | 2 to 3 roles, multi-tenant, 2 integrations, notifications | 55,000 to 80,000 | 12 weeks |
| Demanding MVP | Enterprise SSO, audit logs, public API, stronger compliance | 80,000 to 100,000 | 12 to 14 weeks |
| Cloud infrastructure | Hosting, database, email, monitoring | 100 to 450 GBP per month | Ongoing |
| Post-launch iterations | Fixes, pilot feedback | 5,000 to 12,000 GBP per month | 3 to 6 months |
An MVP under 30,000 GBP exists, often built in no-code or by a single freelancer, but it struggles as soon as B2B buyers send a security questionnaire or demand strict data separation.
The team and the 12-week plan
| Weeks | Activity | Roles involved | Deliverable |
|---|---|---|---|
| 1 to 2 | Discovery, interviews with 10 prospects, prioritization | PM, designer | Validated problem, prioritized backlog |
| 3 to 4 | Wireframes and clickable prototype | Designer, PM | Prototype tested by 5 pilots |
| 3 to 4 | Technical foundation: auth, multi-tenancy, CI/CD | 2 devs | Staging environment |
| 5 to 9 | Core features in 1-week sprints | 2 devs, PM | Demo every Friday |
| 10 to 11 | Billing, onboarding, product analytics | 2 devs, designer | Beta version |
| 12 | QA, go-live, onboarding the 10 pilots | Whole team | MVP live |
The product manager is the role most often cut to save money, and the one that prevents the most mistakes. Without one, the founder must spend 15 to 20 hours a week arbitrating the backlog.
Funding the MVP: support schemes and net cost
| Scheme | 2026 amount or rate | Main conditions |
|---|---|---|
| R&D tax relief (merged scheme) | About 15 to 27% net benefit on qualifying spend, higher for R&D-intensive loss-makers | Resolving technological uncertainty, UK company |
| Innovate UK Smart grants | 25,000 to 500,000 GBP, competitive | Innovative project, co-funding required |
| SEIS for investors | 50% income tax relief on up to 250,000 GBP raised | Company under 3 years old, investor eligibility |
| Start Up Loans | Up to 25,000 GBP per founder at 6% | Personal loan, mentoring included |
| Pilot pre-sales | 2,000 to 10,000 GBP per customer | Letter of intent or prepaid annual plan |
Innovate UK competitions take 2 to 4 months to decide: apply before signing the development quote.
Mini case study
James, 38, former procurement director at a large industrial group, launches a supplier contract management SaaS in London. He chooses a standard MVP at 70,000 GBP with 300 GBP per month of infrastructure.
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SEIS lets him raise 40,000 GBP from angels on attractive terms. R&D tax relief applies to about 50,000 GBP of qualifying spend, returning around 10,000 GBP. Three pilot customers prepay a 5,000 GBP annual plan, i.e. 15,000 GBP. His own net outlay drops to about 5,000 GBP plus infrastructure, and he pitches investors a product used by 10 companies after 12 weeks.
FAQ
Can a B2B SaaS MVP really ship in 12 weeks?
Yes, if scope is limited to one core journey and priorities are frozen by week 2. Projects that drift add 4 to 6 weeks and 20 to 30% to the budget on average.
Freelancer or agency for an MVP?
A solo freelancer costs 25,000 to 45,000 GBP but concentrates risk on one person. An agency at 55,000 to 80,000 GBP brings product management, design and code review, which matter when facing B2B procurement.
Which tech stack should we choose?
Next.js or React on the front end, Node.js or Python on the back end, PostgreSQL and UK or EU hosting cover 80% of B2B MVPs. Infrastructure stays between 100 and 450 GBP per month up to a few hundred users.
Do I own the code at the end?
You should: require assignment of intellectual property and access to the Git repository from day one. Investors check this during due diligence.
What comes after the 12 weeks?
Plan 3 to 6 months of iterations at 5,000 to 12,000 GBP per month to turn pilot feedback into a sellable product.
Let's scope your project. Describe your target problem and first prospects, and we will propose a 12-week MVP scope, a GBP budget and a funding plan. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
