Thanks everyone! ~~HappyMummy~~ re furminator, exactly!! Its crazy, where do they get all this fur!! If you could please send me the groomers name it would be fantastic. They are very placid cats and don't freak out for their vet checkups so we might be ok to just hold them and hope for the best.
DH and I just said we could get some clippers and try at home first - they would be most comfortable here and are completely trusting with us (hopefully we won't ruin that for them!). usandthem, hopefully we will be lucky like your sister!