I'm based in Hull at the moment so another vote for Yorkshire though I'm a dirty southerner in reality. I suggest either Leicester, Nottingham or Northampton, smack bang the centre of the UK, and let's be honest, London is not only a logistical nightmare but a pain in the arse for long distance. And we'll never get a decent venue. Nothing goes on in either of those three, we'd be the party of the decade at least.
We'd need to do a bit better than meeting up and going, "Hey, I'm 'USERNAME', I post once in a while on an internet forum". I suggest booze, food, copious gaming equipment, and celebrity guests like...Susan Arendt! I bet they'd be well up for a trip to Blighty! Let's get it happening guys...