Its a bit of both. Its a uni camp, hence its not like a high school camp where we make you do a lot of things you don't want to and stuff. There are some compulsory activities such as the uni talks and the group building activities, but these will be highly beneficial to you of course. As for the fun and recreational activities (which is about half the time your at camp), those are pretty much optional and its like free time for you to do whatever you want.
If you can't go to camp, and your a recent school leaver, then you should write a letter to the Associate Dean of the IT faculty (details in camp booklet) just to say why you can't go. You have to do this by next week.