After having removed the clutch (it came off very easily with only slight assistance from a pry bar) and had a good look at it, it doesnt seem to be in too bad condition at all. The pressure plate is covered in rust around about 65% of its circumference, but should clean off fairly easily. I'm intending to immerse the friction material in a solution of citric acid, which I've found to be excellent as a rust remover. A quick wipe down in clean water and then thoroughly dry it out over a radiator and it should be good to go.
The inside of the cover plate and the flywheel have similar amounts of rust, but I think a quick lick over with a wire wheel in a cordless drill should clean that up.
And having looked more closely at the release bearing, the 'wobble' isn't in the bearing, but the housing. The bearing itself spins freely without any noise, so that seems serviceable as well.