There's a folk festival on at Sidmouth in Devon from 29/7/05 - 5/8/05 ("sidmouthfolkweek.co.uk") which has always been one of the best, if not the best in the UK.

Don't forgot Ireland as well, if you have the time - but that may need another trip to really do it justice!

There's plenty of info available on the internet, try the "mustrad" website for a start.