I've been a regular at the sessions in the Ben since New Year and although I must admit to having a similar experience some time before Christmas there are a few things I'd like to point out (take them into consideration if you will).

1) I wasn't there the night you're referring to (I'm assuming you were there on Sunday as your comment is dated Monday)
2) It is very unusual for someone to sing at the Ben's session, hence the mixed response, and as for them talking - it's a session in a busy pub, there's going to be noise.
3) If someone's obviously leading the session (folk get paid to on some nights) they'll be trying their hardest to accomodate everyone and get everyone playing.
4) Yes the players are predominately young ones (from the RSAMD and Strathclyde traditional music courses) and fair enough it can seem a bit of a clique to a new player due to this but stick with it (every session's the same).
5) I'm aware it's incredibly unsocial of me to say this, but one of the things my tutor taught me when I was in my early teens and starting to go to sessions was to just follow the crowd and not make yourself standout by doing your own thing unless invited to by the leader(s). Doing so makes you exclude them.