I'm coming for a little visit (about a week) to London from Finland early June with my partner and started to wonder if we'd manage to do some workout at some gym during the trip. As our budget is kind of a low (looking for some couch surfing for the sleeping too, if we could find some nice people there) the question is whether someone could recommend some cheap and decent gyms at central London? Also don't have anything against some vegan training buddies

Any answers, suggestions, recommendations etc are all very welcome! Would be happy to get some pm too if someone wants to send such.
Thanks!