The following links may prove helpful:

Farm Retail Association. Representing farmers, growers and food producers selling direct to the public.

National Farmer's Union. The democratic organisation for farmer's and growers in England and Wales.

Big Barn. On this site you can put in your nearest town or postcode and find your local Farmer's market, Pick Your Own, Farm Shop and even Box Delivery service.

Real Produce. A site putting customers directly in touch with the producers.