Eysenck's Psychology for AS Level is the most comprehensive book I've read to date- it covers everything you could possibly need. In fact, you could probably teach yourself with it, such is the depth of information here. For students interested in studying Psychology at university, this is an excellent text to break down the preconceptions that Psychology is all about Freudian principles. It explores the wider world of Psychology and offers an unbiased look at all the major studies necessary for AS Level.
Key studies are both highlighted in the main sections of the book (according to the AQA syllabus) as well as in their own appendix. This has proved invaluable for revision purposes.
Simply put, even if your school or college does not recommend this book, it should be regarded an essential purpose!