If you're worried about your inability to dance - nobody really dances. It's kind of more like everyone awkwardly bounces together.
If you drink enough to be drunk but not so much that you're ****faced then you should be able to get into a good, carefree and easygoing mood, and you shouldn't overthink. If you worry too much and get too self-conscious you will struggle to enjoy yourself.
If you've never been clubbing before / don't know how to dance then just tell your new mates. You can laugh about it and you might find that they'll dance with you. Most people who are new to clubbing / dancing just stand in the dance floor and take the mickey out of other dancers (usually a sign of self-consciousness), but everyone's a bit drunk and nobody really cares.
I don't like clubbing to unfamiliar dubstep stuff because that's when it is about the music and dancing, but I enjoy singing along to songs I know and dancing with my mates.
I'm sure your friends won't judge you if you're new to clubbing / drinking especially if it's because you're dedicated to your sport (which is impressive rather than negative, there will be a lot of people there who haven't been clubbing because they didn't have a social life in school, etc.)
We had a guy who lived in my halls in first year who would get really drunk because he would just keep drinking, and it affected him worse than most because he didn't drink often (he was an athlete and squash player), and he was still fun to be with. I think it's in your best interests to just be honest about your lack of experience with clubbing because then your friends might keep a bit of an eye on you and just not pressure you to drink too much (which is always a good thing). They might be surprised you haven't been clubbing before but I'm sure they won't make you feel ashamed of it. Dedication to your sport is a totally legit reason to not drink often.
Ultimately, clubbing is just about letting go and enjoying yourself, and you can only really enjoy yourself if you let your insecurities go and just dance. This is why so many people need to be inebriated in order to enjoy themselves, because they can't let go of their insecurities and self-consciousness without alcohol. I wouldn't advise you to drink to lose your inhibitions, just remember that everyone is looking for a good night out, and nobody will notice the things you feel embarrassed about except you.
And if someone does seem to be taking the piss out of your dancing, it's probably not that you're a bad dancer, but that they're an insecure one.