42 page introductory guide to ESA – http://freepdfhosting.com/4577fda9a2.pdf
Please consider joining www.benefitsandwork.co.uk who create these guides. They often offer discounts on annual membership. Being a member gives you access to their forum in which you can ask questions. If your question is too personal or not included in the forum already then you can send a private message to their staff who are extremely knowledgeable.