"The Glider Pilot's Manual" by Ken Stewart is another good one, I believe. It's the standard ab-initio text book at my club. Never read a copy though.
I've got "Gliding" and "Understanding Flying Weather" by Derek Piggott, both of which are must haves, and the BGA Manual which is more to do with the technicalities of things. Still good though. For more advanced stuff, I've read "The Soaring Pilot's Manual" also by Ken Stewart, which is very good indeed.
As for websites the most important by some way is
http://www.itadvice.co.uk/weatherjack/STARS.htm
Which is Jack Harrison's gliding weather forecasts.
Have fun using your feet.....
Cheers
John