How to come to hackspace
You don't have to be a member because there are open days on Tuesdays evenings. For other days you have to be a member, though there are events, you can come to events (like create-a-con) without being a member.
Become a member
It depends on how much you do, if you come not very much you can pay less. If you come a lot you pay more. It's roughly £10 per month.