Don't know if they still do it, but my lender (intelligent finance) used to offer mortgages that went above the normal 25 year term. In theory you paid more as it was longer, but they were (are I should say) also flexible about overpayments, so the cost needn't be restrictive.
Given how hard it is nowadays to actually buy something, I'm sure there must be ways of getting one other than the standard deal. A mortgage advisor (independent one that is) would probably be your best bet.