The great thing about the period just after Christmas is all your Northeners and Midlanders and what have you are all still back home in the hills so you kind of get London to yourself. It's just like being Will Smith in I Am Legend, but totally and completely different.
Annoyingly a lot of people will be back for NYE. This event is somewhere in Hackney. Apparently you need to sign up to a list to get in. Do that here: http://www.troubled-minds.com