Going to London!

Next weekend, that is from Thursday 30/8 till Sunday 2/9 (long weekend!) I’ll be in London with my female best friend. I’d also like to go there with my boyfriend but next time... He couldn't come anyway. With my best friend we‘ll have lots of fun and I know we‘re gonna have a great time. Can anyone suggest me of some nice, trendy bars /clubs or parties to go out (we‘re 30something), but a place that she won’t be the only straight woman there?