I borrowed that book from college for my LNAT, and to be honest, i didnt find i helpful in teh slightest. All it can do it get you used to the format of teh questions. It cant help you prepare any more than that as the questions on teh day will be so obscure.
I'm positive im right when i say that one of the major points in unis using LNAT is the fact taht you cant prepare for it as you can for A levels etc. This way, they can test if you have teh skills they are looking for, and you can't fake it by doing hundreds of practice papers and becoming an expert at jumping through hoops, as most of us did with A levels.