< Shhh,! This is a library! Err, wait... no...
I've noticed you across the room. I'm the one with the notebook usually open in front of me and a vacant look on my face, occasionally sipping one of the Pub's excellent porters. I'm also an introvert also, and like you I can bluff it when I need to, but that's taxing. Come over and say Hi if you're in the mood, and now that I know your name I'll say Hi as I pass on the way to the bathroom.