I've found a way for people who can sleep on overnight buses/coaches to save time and accommodation by taking night coaches out of London.
I've haphazardly found Plymouth-Penzance, Liverpool-Blackpool and Glasgow-Edinburgh by guessing that they're cities large enough and far away enough to possibly have such service, but is there a quick way to find a list of all UK overnight services by National Express, Megabus, Easybus etc to places tourists are likely to visit?