Welcome to APUG. I did a City & Guilds course a few years back and really enjoyed it.
Before I set up my darkroom in a spare bedroom I used to use the bathroom for printing. I placed a sheet of 12mm MDF over the bath. The enlarger went on top with the trays next to it. I could just about wash 10x8s in the hand basin. I blacked out the window using thick black plastic sheeting, which I think was designed for pond liner. B&Q or somewhere should have some, or you could try double thickness bin liners.
I ran an extension cable from the landing under the bathroom door for the enlarger and safelight. The gap under the door was blocked by a towel. It wasn't ideal and there were some light leaks so I had to restrict printing to evenings. Perfect timing for you as the clocks will be going back soon!
There's still a few places left that'll sell you a changing bag -- plus you can try eBay. The place I use is Firstcall Photographic at
www.firstcall-photographic.co.uk, I think Jessops may even sell you one but you'll have to order it and knowing them it won't be cheap!
Hope that helps and keep the questions coming
Mike