Well I can't really comment on manchester gay clubs, but i certainly can on the ones in London. I go quite a lot, at least 2 times a week, sometimes 4+. well anyway, I for one have never been offered sex in a toilet (although i have been offered a bj on the bus home afterward..
) and have never seen it happen, because there are always toilet attendants that will stop you going in together, and if you somehow get in, you will be caught and kicked out. In fact the staff wondering around the club will tell people to stop any particularly heavy petting. This is the same for str8 clubs too. Security is quite high in London clubs.
And to OP, this may be too late, but I don't see why you have to go now? Can't you wait til uni when you can go with the LGBT? If its Imperial you're going to, I know that club nights are planned with loads of people, and everyones really nice
If its UCL, then i know loadsa ppl there, and theyre nice guys too and will probably be going out too.
Going alone probably isnt the best plan, as it can be quite un nerving. The first time i went i went ith 1 friend, and it was such a change from straight clubs. People are much more forward and look at u and grab u occasionally, whihc may freak you out somewhat. I lost my friend on this occasion and ended up dancin, with like 4 30ish old guys dancin around me, which freaked me out so i rn away haha.
And with goin to a bar instead, this may be better idea, but be aware that being so young, you will get lots of people looking at you probably and you may feel rather self conscious, i know i do when im there. But hey, you may love it haha.