This website is a useful source of information, with links to Edexcel the awarding body and the publishers.
For a Gateway page with links to lots of useful stuff see All about SNAB
In many biology courses, the biological concepts are presented, and examples or applications are given at the end.
Salters-Nuffield Advanced Biology introduces a context and then presents the biological concepts needed to understand what is happening. This makes the relevance of the biological knowledge immediately apparent to students.
For more about this see Introduction to SNAB