Not sure about classes, but there are a few forums and places.
you might like: http://www.thepoetryforum.co.uk/forum.php
(Geoff and myself participate there)
but they seem to be being picky about letting new members in (as Geoff will attest).
also you might check out the Poetry group at Goodreads:
I could also recommend a few instructional poetry books if you like.