i know this is a pretty old post but I don't really see how there can be. We live in a 3 bed detached at the moment that is about 5m wide. I've seen narrower ones though. I suspect that if the design passes the planning stage then it should all be fine.
Again, I know this is an old post, BUT... under Part M of the building regulations, the internal dimensions MUST be designed to facilitate a wheelchair user, IE min 1200mm turning circles, adequate downstairs WC provisions etc.
Best advise is to get an architect or LABC comments.