Try not to worry until you get there. I'm a rising 2L with two small children. I was worried that I would have nothing in common with my classmates, but I have made some really incredible friends. I was pleasantly surprised at how mature and interesting my classmates are. Of course, there is still a great deal of partying that goes on- who could blame them? Still, even though I don't participate in the "extra-curricular activities," I think most of them understand that I just have other responsibilities and respect that I have my priorities in order. (I hope).
Also, you might be surprised at how many others aren't "trads." There are a lot of parents, married people, and older students that go to law school. You won't be the only one, I promise!