Are they entitled to any state and private pensions? Do they have any family/ friends who would provide assistance in future if they lived close enough? they should choose somewhere suitable for their old age as moving is expensive, particularly if they buy a house. So ideally one floor, adaptable, can walk to shop, good public transport or everything close enough to walk
£6K a year for 20 years? That's pretty tough. And what happens if you live longer? To keep rent under perhaps 50% of your outgoings (ideally less) while still being in a city, maybe for example Lincoln?
Might be best to try to buy somewhere for under £60000 with two bedrooms and rent out the other room? I'm really guessing where that might be possible - a few probes on rightmove and there do seem to be some, I saw some in Crewe - Leek - Grimsby - but I don't know what the areas would be like and whether you'd be able to rent a room easily without making yourself vulnerable. You'd still have to live a very, very frugal life but I think it would be possible.