check out "Folk song in England" by A.L Lloyd (Lawrence and Wishart). This will lead you to about 90 other books on the subject. You could also try the English folk dance and song society libraries (if I was really clever I would give you a blue clicky thing here). If you want recordings there is no finer starting point than the Topic Records catalogue (now 60 years old).
Topic Records Ltd, 27, Nassington Road, London NW3 2TX.
Happy hunting! You are about to discover the richest musical tradition in the world.
Melodeon