I want to purchase a good health and safety book which is aimed at diploma/degree level, but unsure which one to buy. Does anyone know of any good health and safety books?

There's only one choice: Safety at Work, Ed John Channing. The 2013 edition is available from the Brazilian website for £114. This is what they say about it: The leading book on the subject of occupational health & safety revised in line with recent UK legislation and practice. New to this edition is the foreword by Judith Hackitt CBE, Chair of the Health and Safety Executive and a brand new chapter on the latest EU and international regulations and directives. Safety at Work is widely accepted as the most authoritative guide to health and safety in the workplace. Offering detailed coverage of the fundamentals and background in the field, this book is essential reading for health and safety professionals or small company owners. Students on occupational health and safety courses at diploma, bachelor and masters level, including the NEBOSH National Diploma, will find this book invaluable, providing students with the technical grounding required to succeed. Edited by an experienced and well-known health and safety professional with contributions from leading experts in research and practice.

I don't think you get a comprehensive overview in a logical format from simply browsing and putting together articles and bits & bobs. Neither would I consider forum viewpoints to be definitive, and they will only relate to a specific aspect in any case. So you do need at least one good proper book to read, refer to for the course, and then dip into forever. Although eye-wateringly priced, and it will eventually be outdated, the HSW text mentioned is the usual 'bible'. I would also recommend supplementary reading of (for example) Boyle, Reason, Difford, Long, Ball, etc. for degree level, not necessarily purchasing unless smitten. If you can get access to some of these or similar through a library, this is good. IOSH also do a couple of books worth looking at, to support NEBOSH study. You can get to look at many publications in the flesh at the Expos. The articles in SHP can be useful too, especially the CPD ones, if you are already able to access these. Have you looked in the study forum for tips?