I dont know if they trim claws, are they indoor cats? Outdoor cats usually keep theirs down by walking on pavements and sliding down walls when they get down off a roof or something. If they are growing back on themselves and digging into their paws then the vets might do something - but the PDSA is a charity with limited resources and they might not because it wouldnt be considered an emergency - but give them a call to check.
I don't blame you for not attempting it yourself. We have just tried to give an antibiotic to one of ours. We have tried everything known to man and she has still gone off sulking, hissing and with a tail that is doing a jolly good impression of a bog brush lol. Even our trusted syringe method has failed as she has an abscess in her mouth so I suppose it is an injection for her.
Cats are pretty ferocious creatures or is that stating the obvious.
aw bless, both cats are brillent with tabs. But my Naomi especially she has really sensative front paw and she will yell in pain so fingers crossed for the vet. She also hates the vet and last time flipped and turned over in the air and scratched the vet. But she is a very good pussy cat normally