My band are looking to get some one colour screenprinted t shirts (probably a run of 50 or so). Do any of the UK forumites know of/have experience of somewhere to get this done for a half decent price?

As far as I can tell, my city (edinburgh) doesn't have ANY screenprint places at all

You could try some of these places:

http://www.google.com/search?client=safari&rls=en&q=edinburgh+screen+printing&ie=UTF-8&oe=UTF-8

I've had good experiences with Talking Ts.

Try Mark (or Poppy) at Shock Tees. Tell him Adam from nub recommended him and he might throw in a few dodgy serial-killer freebies!

He does short-runs and stuff, and he's into left-field music...