I don't mean to be disrespectful of your opinion, but it's really your T's opinion that counts here. Most Ts would discourage contact outside of the session like you're talking about. They would talk to you briefly and that's all. You could try to talk to them longer, but it probably wouldn't be good for you though you may like it. I always went up to my T to talk at one of the functions I saw her at. I felt safe talking for a few minutes, and I was aware of where she was sitting. But she didn't want me to socialize with her because she was my T, not my friend.