Ideas for our StHen do

Hoping you can help us with some suggestions...Originally we weren't going to bother, but as time has gotten closer we've both decided that it would be nice to have a night out just before we get married. Most of our friends are mutual now, and the vast majority are either married or in long term relationships and it seemed silly to split everyone up, so we've decided to have a join Hen and Stag do. The only problem is we're at a loss as to where to go. Dinner and then a night out is going to be too expensive for many of our friends, so I was thinking just a night out in a lively bar? Anyone got any suggestions for either London or Essex (Please NOT the sugar hut, we wouldn't go there again if you paid us!!!)