try Potters
Potters Poultry, Wot-A-Pullet, Country Fresh Pullets. There are loads of pullet rearer's that will rear part organic but I believe only Wot-A-Pullet rear full organic birds.
Piggots are the only supplier I deal with for meat birds. Another one I can highly recommend for layers is in Devon had a lot of top notch birds from them no issues cracking and good service http://www.organicpullets.co.uk/organicpullets/index.html