The lease for the flat was only granted a few years ago so am I correct to assume there will be no problems with the lease?

Because the lease is new does not mean that it is correct or compliant with mortgage lenders requirements and  we will, need to carefully review the terms of the lease. Some conveyancing may well take the view " if its new it was probably looked at so on the balance of probabilities it should be fine ". That is simply not the Friday's approach. Remember a lease is a diminishing asset. The lender will want to know the length of the unexpired residue of the term. As a general rule, a lender will not lend against a lease with less than 60 years remaining at the date of the mortgage. If the lease has only a short unexpired residue we would consider whether or not you are able to take advantage of the statutory regime that allows tenants, in certain circumstances, to obtain a lease extension.