National Union of Teachers (NUT)
Association of Teachers and Lecturers (ATL)
National Association of Schoolmasters Union of Women Teachers
Voice – The Union for Education Professionals (formerly PAT)
Advice and Support
SupplyBag.co.uk - The essential resource for supply teachers. Information, advice, support, books, top tips, a dedicated support forum, and a supply teaching agency database.
Education Support Partnership - Independent, confidential, 24/7 support to everyone working in education
Supply Teacher Network - my own Facebook group, it's all chocolate and marshmallows at the end of a hard day's supply!
TES Connect - dedicated supply teacher forum. Quite political, can get heated!