Useless degrees

Not necessarily, depends how much "contact time" the course involves, and how it's distributed over the course of a week.

If you classes are Mon, Tues, Wed, it might be worth renting a flat/room up there for just staying over Sun/Mon/Tues nights.

I think that's extremely unlikely, but I'd be happy to be proved wrong. It seems quite simple--if you do it part-time, it should be possible to stay in London. If you do it full-time, it won't.