Outside of forever hypothetical situations devised on messageboards, where a night out can reasonably be limited to "(cheapest) plate of food and 2 drinks", and ends up being more like "plate of food, ooh and those deserts look good, and that was 3 drinks during the meal to wash it down, and now for another 11 drinks, and buying a round for those guys I know from... er... somewhere... and those drinks for those nice girls I thought I had a chance with... and the entrance for the club, and the cloakroom, and some more drinks, and a kebab, and oh screw the nightbus let's get a taxi", it's pretty hard having a night out in London for less than £100.