Cider & Cider Makers
CAMRA's Definition of Real Cider and Perry.
CAMRA has produced a definition of real cider and perry to reflect the current practices and processes of cider and perry makers across the UK. You can find all the resources you need to make sure your cider and perry is #NotFromConcentrate.
https://camra.org.uk/campaign_resources/camras-definition-of-real-cider-and-perry/
Cider and Perry Producers
CAMRA maintains the most comprehensive list of real cider and perry producers across the UK. These are categorised into "Cider and Perry Producers and Suppliers" and "Producers of Fruit and Flavoured styles of real cider and Perry"
https://camra.org.uk/beer-and-cider/cider/promoting-real-cider-and-perry/
You can check if a cider or perry is real using CAMRA's map of cider & Perry producers:
Map of Cider and Perry Producers and Suppliers
Kent Cider Makers.
A comprehensive list of the Kent cider makers can be found on the Kent CAMRA regional website.
CAMRA Books.
If you want to expand your knowledge of cider, why not have a look at CAMRA's book store.