Take it from a musician
I've spent a lot of years on stage looking out at the crowd & one thing I know for sure, most people can't dance. I'm not saying this to poke fun or anything, it's just a fact. Dancing I've heard said is a "vertical expression of a horizontal desire." Now if you want to dance with the same sex I guess that's okay but I don't want to watch if you're a guy:p
Just relax & don't worry about if you're good at it or not, chances are no one even cares. It's all about having a good time. Who knows, you may start a new trend.
On the rare occasion my bassist is asked to dance:p he usually replies "that's why I play music, cause I can't dance." I feel sorry for the guy cause he's a person that can play so many instruments from trombone to GTR, drums, piano, mandolin and of coarse bass. On top of playing well he can sing and work lights at the same time & do it all well. But here is also a guy that took dance lessons with his wife not once but twice and the instructor even told him he can't dance. Go figure!