Try the venues/festivals pages on www.folkandroots.co.uk, which covers all of England. The London and Kent sections give a particularly good layout of what is available, over the whole range of concert type clubs to small local pub sessions.

A few phone calls will be advisable as some venues do disappear without letting the website people know, and there's nothing worse than a half hour trip to a club that died last year.

Do have a great time while you are down this way

Good luck
Don T.