Keeping Pet Chickens which is written by the Eglu people and
Starting with Chickens by Katie Thear.

Both very good in their own way. The Eglu one is aimed more at children I think in as much as it is full of glossy pictures but it does hold a lot of useful information. The Katie Thear is a wonderful book, a fairly balanced view stating pros and cons of chicken keeping crammed full of useful bits and pieces.

I also have a book on making Hen Houses, which I use as an idea resource.