Thanks to everyone for all your advice. Kitten went to vet yesterday, she does have fleas, so he did an advocate spot on treatment for her and we now have enough for the next 3 doses, along with worming stuff and regime.
I sprayed the room she was in last monday with the 4Fleas spray, but bought some Indorex yesterday, and now that she's treated plan to do the rest of the house (do I need to do the living room again?).
As for food, vet says she is fine on a dry diet and he was pleased with the food she was on (Hills Science), she does not need wet food, but if we want to give something occassionally then chicken, tuna or prawns (cooked) best.
We asked about the legalities of buying from a pet shop. He said it is not illegal, but not encouraged as you cant be sure the animals have been treated fairly or kept in good conditions. So, I cant report the pet shop.
But lesson learned the hard way, and if I could turn back the clock, I would have pursued getting a kitten or cat from a pet rescue place, for peace of mind.
However, the kitten we have has a really lovely nature, and I am sure she's going to make a really nice family pet.
Just a last bit of advice from those of you that have used Indorex, on the tin it is very vague and just says remove pets, spray and ventilate room. Do I need to vaccum before and after also?
Thanks everyone again.