I dislike the idea of dressing sexy and going out to clubs or raves or anyplace that is crowded, sweaty and rowdy. However my first week of Uni is coming up soon which means Fresher's Week which means several nights out of clubbing and partying. I do not want to go but am unsure as to whether I should just learn to like it as it means missing out on socialising. I feel outcasted as I know few people who aren't interested in clubbing, whilst my interests are more mature for my age I suppose e.g theatre.

I honestly dislike it too. I just dislike the idea of going out and making a fool of myself, so to speak and I think a lot of people feel the way you do too. What I would do, is to give it a try. It seems as though you're not interested in it at all, but once you go out, you may end up having a good time! You might even pick up chicks as well as making new friends!
That's the negative - now the positive. My university has a huge range of societies, groups and clubs, ranging from sporting, music, film, politics, theatre, LGBT, etc. And if there isn't a club which matches your interest, start one.
There's nothing to say that the friends you'll probably end up living with in your second year and beyond are going to be doing to same course as you (in general, that doesn't happen). It'll be the people with the same interests.
I wouldn't avoid Freshers Week entirely, but it's not going to define who your friends are during your higher education.
But yes, youre normal for having an opinion and a like or dislike for a particular topic or hobby. Nothing wrong with that.
The good thing about finding those people, while they're harder to find, they often end up being better friends.
Just remember to be YOU. If your friends insist on dragging you to places that they know you don't want to go, they aren't your friends. Find new ones.
Lastly, get comfortable in your own skin. Hanging out alone and doing things that you enjoy can be very relaxing and pleasant. Don't be afraid to have plenty of "you" time.