Contra is now pretty popular amongst folkies in the UK (well, England, anyway). Ceilidh (around the UK) is the wander-in-and-give-it-a-go thing, less taxing and more energetic than contra, and should be very welcoming and age-blind. (Less chance of throwing a whole set if you get it wrong, and typically less intricate.) I guess with most genres you'd feel at home joining in somewhere else. The big long festival of folk dance/music in England should have been happening from this weekend. There's plenty of video of Sidmouth Folk Week on youtube^Winvidio.us if anyone's interested, though more of the displays than the social dancing.