Hi Fluffy Robot,
I'll PM you, but for the benefit of anyone else in the area as well:
It's at the Thomas Wall Centre on Benhill Avenue (postcode SM1 4DP). It's quite central, only a couple of streets back from the High Street, behind the St Nicholas Centre.
Starts at 6, goes on 'til 10, usually £2.50 to attend but first time's free, so nothing to lose People play pretty much anything, including Magic, 40k, Infinity, various roleplay games, and of course Malifaux. Everyone's welcome, it's pretty informal, just turn up and play.