If you know the owner of the tortoiseshell advise them that you will bill them for any food it eats and damage that it causes to your house.
If it is a stray, complain to the council that it is a wild cat and you are afraid of it when it comes into your kitchen and that you want it caught.
Owners are responsible for their pets and should not have cats if they can't control them and they cause nuisance to their neighbours.
Cats loose by themselves are noisy, defecate on other peoples property, eat pond goldfish and birds and in my opinion are a bigger nuisance than dogs.
Incidentally, I have two cats myself, but I don't let them annoy any neighbours. Cats are cats - but it is the owners who should be penalised.