I've been doing it from my home, but London does have a bike co-op that I just recently donated 3 bikes to (Squeaky Wheel Bike Co-Op). I've only been there the one time but plan on going back, and potentially looking to volunteer there and help with their Bikes for Newcomers program if I can. Just need to work out scheduling and all before inquiring further about it. I know they have a volunteer night on Tuesdays to go in as well.