Ian's suggestion of the auction is a good one. Also any Cory groups in your area may have some panda breeders. Ian certainly is much more aware of UK sources than I am--as a matter of fact he may be more aware of sources in the States!
I am not sure about the CR--possibly the Chech Republic, code for farm and hormone bred. C may be China another source of puppy mill fish.
F1 are fish spawned from wild caught fish. They often make good breeders of healthy fish although they may be more sensitive to water condition differences from their breeding tank than wild caught. But on the other hand wild caught are reputed to be more difficult to spawn in the aquarium. I have mixed the two for breeding groups with good results by adding wild caught to breeding groups optained from more experienced breeders.
Oops!!!
The C. is for Corydoras. C. panda = Corydoras panda