I'll just give some background, im 18, live in the UK, average height etc, go gym play tennis enjoy gaming hopefully going to uni in september...
Any way I like a girl in my maths class, but im not sure what to do, i cant tell if she likes me or not, we got on and talk a bit, i get on well with most people (not trying to boast or anything!) and im not sure about the best way to tell her or say something to her about it, any advice/suggestions??

It depends on the type of woman she is. You can ask her on a date (dinner and a movie or the like), you can be more casual by saying, "I like you more than a friend; how about you?", or you can be more aggressive: corner her surprisingly against her locker/a wall, put your right hand on her so your fingertips are on the spine of her neck, thumb and palm resting on her cheek, and whisper in her right ear, "You are the only woman lascivious and pulchritudenous enough to slake my unbridled paphian desires. I want you." As you pull away and walk to your next class, draw your hand downward from her face to her chest on the left side near her heart (but definitely before her breast).

Considering your relationship now, I'd say that option A or B is more viable.

the problem is im too nervous and without confidence lol :/

Pretend that this isn't true.

Genius.

Anyways, are you guys friends at all? Sometimes it can be a make or break kind of thing. Sometimes friends can lead to "just friends", but other times it'll give you some time to get comfortable with her, if you're shy. Once you're comfortable wit her, just ask her out on a simple date. Any sensible girl will say yes, and just see where that first date leads you. If you're comfortable and feel really confident about this girl then just keep moving forward. Not too fast though, not saying you should inch along in the relationship, but figure out her boundaries. Personally, in most relationships I've been in, it works better to learn her boundaries and follow a pace she's comfortable with. Don't really push her to do anything unless she's really shy and not very experienced in relationships.

haha ok i'll give it a try, thanks for the advice

Confidence is key.

No, really, while it's important to not go rushing in full-throttle and scare her off, it's important to be confident in wanting to try to move things forward. If you keep dancing around it and never assert yourself, always opting to be passive and hoping things will just fall into place, you'll only set things up for failure.

As much as you may be nervous to make a move, understand that she's just the same - even if she seems like she's more the aggressive sort. Everybody is nervous to go out on a limb for a relationship - it's just some people are moreso than others. Having the confidence to do so will leave a positive impression; even if she says no, she'll still at least respect the fact that you were up front about it. On the other hand, if you shy away from it, trying to force her to make the first move, you'll likely leave a negative impression that will make her feel like you're not interested ENOUGH to make the first move, which is not how you want things to start off.

Easiest casual date; pick a store. A department store or an electronics store works great. Browse the movies, books, CDs, games, whatever... and point out some of your favorites, ask what she thinks of this one or that one. Get her talking and enjoying the time together. Don't even need to call it a date. "Hey, I'm heading to [store], you wanna tag along? Maybe they've got some good movies on sale or something."

If nothing else, aim for getting things such that she knows she enjoys spending time with you, and does so more often than spending time with other friends. As long as she's having fun, she'll see some level of possibility in it.