Yes, it's possible to get a mortgage with a 5% deposit for a flat, particularly with the support of schemes like the UK's Help to Buy. However, the availability of such mortgages can depend on the broader economic environment, the lender's risk appetite, and specific criteria of the flat (like lease length and building condition).
With a 5% deposit, you'd be looking at a 95% loan-to-value (LTV) mortgage. While these mortgages offer the benefit of a lower upfront deposit, they typically come with higher interest rates than mortgages with a larger deposit, as they represent a higher risk for the lender.