I can’t tell what it might be. I normally go on head shape and eyes, fangs, body shape, habitat and colouration. I can’t see most of those in the photo.
UK spiders are pretty harmless though. They have small fangs and very mild venom. I can’t tell what that one is but it’s not one of the more nasty UK ones. You could try looking here again
http://www.uksafari.com/spiders.htm
Yours looks like an adult too, so it is probably coincidental you have found 3, rather than a nest dispersing and young leaving home ( not sure if that bit of info is reassuring or not 🙂 ).