Dan Barnard of Event Sound Solutions is brilliant! Through having friends in common Ive heard him play a few times and he really knows how to get a party going. And more importantly, he really listens to what kind of music the host wants (I've been to quite a few weddings where this had not been the case!). Can't recommend him enough.
From the website I can see that he can provide equipment too but if you don't need that I'm sure he'll be up for just DJ'ing
http://www.eventsoundsolutions.co.uk/

We recently used the Mobile Music Company run by Steve Lewis... The dj we had was great and managed to incorporate all of our special requests. You should be able to find him on google!

We are looking for a DJ for our 40th Birthday party in (early!) September. Can anyone recommend someone? Thanks