Even if you don't plan to be a regular, local clubs really are the best places to find local gamers. As good as BGG is, it's quite hit-and-miss as to whether your message will be seen by someone suitable.
I host games, and go to other peoples houses for games, in North London. All of these people I have met through going to the games club in Finchley. If for some reason the club ceased to exist I'm in a position now where I'd easily still get plenty of gaming in.
Yes it does sound like that is a great place to meet other local gamers, just trying on here as another option.
Used to go to a number of Magic events but they just seemed to be ways to get to you to buy more cards and you ended up never being able to play with the cards you had got already. The people running it also didn't like you trying to arrange Magic games outside of their setup, and it seems that Magic is a bit of a bad word in some board game groups.