The link is for a book called avatar: the activists guide book. It was originally given away with preorders of the blu ray, however I've not seen it for sale until now. Technically it's free but you pay 90p postage. You can also send a sae and get it for 50p. Great film, great book. Get it while it's still in stock.
I have hotlinked directly to the offer page, saving the need to register with news of the world amd clicking the same link. It's a legit offer