Mallard,
You're definitely at their mercy. Leave is only authorized (other than emergency) if your class dates fall over Christmas, in which case they let you take a total of about 15 days. I think some classes get liberty later in the program, but even that is pretty limited. There will be lots of other people around, P'cola is a large base, but there won't be any sock-hop mixers!
Check out some of the other threads, there may already be answers to your questions.
LTJG G