Library? Bookstore? I dunno... Maybe that would make you a little less anxious as most people in that environment are sort of quiet themselves. Just don't turn to drinking a lot , which can be tempting. You feel good while drunk and even make some "friends" but the next day or whatever you will still feel the same , yet have to socialize in what people would consider a "normal way" which I know from experience is tough.
The real solution is getting real help if you have SAD. I just now have realized my problem and am in the process of getting help.
I sincerely wish you luck , as I go through the same things you do on a daily basis.(in general)