The English Folk Dance and Song Society website has a great resource bank with materials which could help you.
Even if you're more into Scottish than English folk music, there's still useful information there. We particularly liked the Jargon Buster. There's much more there than just musical terms, as it covers folk traditions, costume details and other intriguing facts. (For example, if you go busking, then technically you're "cadging" rather than begging, ie, you're getting money in exchange for providing entertainment, and not just because you begged for it ... a useful distinction!)