I try and cook from scratch whenever possible, I'm Diabetic, and quite sensitive to some food additives, and added salt in dishes whether natural or chemical soon leaves me dehydrated and itchy.
This rules out using a lot of the sauce mixes, ready meals, and some types of flavourings including cheese. I do buy ready prepared vegetables, especially the more tough ones to chop, but prefare fresh Onions and Mushrooms, as I find the frozen type quite watery, often yielding more water when defrosted than the vegetable itself. One of the worst culprits for high salt is anything with a Breaded coating, even worse if it's one of the flavoured variety, Southern Fried, Garlic and Herb, Sweet Chilli type of thing.
I do use some things like the Sainsbury's microwave rice pouches, frozen Aunt Bessies oven Chips, and Heinz Mayonnaise. Our Meat, Fish, and Dairy produce we buy fresh from local suppliers and freeze ourselves.