My bank
http://if.com/ used to offer a sort of lifetime mortgage, in that you weren't limited to the normal 25 year term but could stretch it over 30 or more providing you were of normal working age. More expensive in one sense, but they also offer flexibility allowing you to overpay, so in theory, you weren't tied to long term interest payments.
I don't know if they still do though, but I've included the link so you can check them out out, and as a bank and a lender, I would reccommend them. The virgin one account
http://www.oneaccount.com/onev3/index.html is a similar type, tho I have no experience of them.