Go for it robinw - it's fantastic. Don't read a book, it really won't help .. you need to be taught. A book might be helpful to read once you 'get into it'. It's very much a lifestyle, teaching you to be always aware of your posture. I had big back problems after having the boys, but also was interested from a performance point of view (singing). The AT means that throughout the day I am aware of my posture and where the strains are, and my back problems have disappeared. (I finished the course 2 years ago, and it is certainly still affecting my life).
Big tip - if you can go for a 'trial session', because if you don't get on with the tutor, it probably won't work for you ... try a different tutor - some are better than others.
Good luck - let us know how you get on.