Hey hey,
If you expressed an interest in coming to this event you should have received an email from Rare/Microsoft. If you did receive this email, then great - see you there.
If you haven't received that email then, firstly I'm sorry, I tried to ensure user group members some preferential treatment but I'm told that many people wanted to go and things got a bit chaotic; and secondly, to ensure entry you should try to arrive early.
Actually, if you want to be sure of getting in you should probably be there early whether you're confirmed on the guest list or not... Doors open at 7pm.
Oh, I've updated the original post with a map link too.
Cheers,
Leaf.