Mate, if you're looking to have a bit of a blowout, go away for a few days, book a hotel, and maybe see a few different girls then firstly, I'm jealous as fuck, and secondly, London is definitely the place to be. Manchester and Birmingham are apparently pretty good too. Our area of the country here in the East Mids is a bit of a dry spot relative speaking - although that's not to see we don't have some fantastic girls pop up from time to time.
But London's near enough that if you've got the opportunity, you'd be mad not to go straight to the source, and get the biggest choice of girls in the country by far.