Another book has just arrived in my email looks exciting but long (and a bit expensive at £30)

Blood and Mistletoe: The History of the Druids in Britain By Ronald Hutton:

"As Ronald Hutton's Blood and Mistletoe makes clear, we like the idea of the Druids so much that we’ve made up almost everything we know about them," says Noel Malcolm.

http://tinyurl.com/pt5h7l

It will obviously be a very sensible book about Druids, but Ronald Hutton is the expert on the subject. ;)