Lisa,
Dot hates me doing the back of her legs and "britches", also her tum. Try and get a comb which has tines of differing lengths - not the ones with big wide tines at one end and narrow ones at the other - the comb you want has small and large tines alternately.
I bribe Dot heavily while grooming. If I put a small amount of cat treats on the floor, I can usually do most of her back end while she is concentrating on snaffling treats. To do her tum I kneel on the floor and put her between my legs (without gripping), with her back towards me and then I lift her gently by the scruff of her neck and quickly comb her tum and chest. To do under her chin, I hold a cat treat above her and as she reaches for it I keep hold of the treat in one hand while quickly combing with the other.
It doesn't work perfectly and she always swings for me at least a couple of times but it's OK. We do play afterwards and I think that helps. The other thing that helps is being really firm about grooming. Dot knows that if it starts, there's no way I'm giving up until either the job's done or I've passed out through blood loss.
Hope some of this helps.
C.