Can I join my church group in a mixed-gender sleepover
Have you asked to join?
I'm a bit hesitant about taking part in the sleepover but I want to have fun.
If it sounds fun, why not? You may not get another chance, so I say go for it.
What if I get certain desires and don't know how to act, especially around others?
Well it is a church event I am pretty sure there will be adult chaperones to prevent that kind of mingling. If you are afraid of this maybe you should stay home then.