I'm in the process of doing my research before buying either a tunnel or greenhouse and bought this book to help me make a decision. It has saved me a lot of time and given me some very valuable pointers. For example, I couldn't decide whether I was best suited to a polytunnel or a large greenhouse. As a result of reading the book I am now buying a Keder house, something that didn't come up during my web searching. This information alone meant that the book was a worthwhile purchase.
There is a very useful list of manufacturers and suppliers and also a list of web resources in the appendix
Don't buy this book if you're wanting a detailed listing of what to grow and when to plant. In some ways I feel that the title of the book could be better, as it is far more valuble to someone who is thinking about buying a PT than someone who already has one erected and in use.