You have to becareful the covens you may join. Other than skyclad, if you arent into this move on.
Some covens I have heard require you to perform sexual riturals and just for it anyway. Be leary of these types of covens. It is by your own right to refuse to do these things.
You should be told inavance sex magick is to be used and you should have the choice to do these. If not move on. Ones that force this type of practice is not true wicca/pagan practices.
Wicca is a religion/Family. You practice your beliefs which have nothing to do with sex. But if this is your choice thats your right. But I would look for other ventures.
Skyclad:
If you join a skyclad coven. It has nothing to do with sex. Its a way of worship. Some believe clothes blocks the energy force. Not saying they still don't practice sex magick, but still its not just for sex. If sex is main factor, then this you should move onto another coven.