This book relates to American Sign Language, not British Sign Language, so probably not useful to most people in the UK.
Anyway, sign language is generally better learnt from watching a person demonstrate the sign so you can see the movement, facial expression and body language which form part of the sign. Books are ok for revision of a sign you already know, but not really for learning. If you can't get to a class to learn, try videos rather than books.
Having said that, if you actually want a book to help you remember American signs that you have already learnt, then the signs in this one are fairly clearly illustrated and explained, so you could do a lot worse!