Chicken and fish should be fine for a CRF cat, as long as it is only part of their food. Royal Canin and Hills renal foods can be bought online from VetUK, but as they are classed as prescription diets, you can't buy them in supermarkets. Zooplus do sell 2 renal foods though, think one brand is Integra, and can't remember the other - but Rosie preferred the Integra to the RC. We had 4 different kinds from the vet, excluding k/d, my vet finds it rarely gets eaten - there was some beef pate stuff in a tray, beef pouches (which I never tried her on, she didn't like beef flavour normal food), chicken and tuna.