If you search on pinterest you can find lists of low syn branded foods.
1% Mug shots are a good incase of emergency as are muller light yogurts.
As previously mentioned precooking batches of chicken to snack on is handy. I buy a 1kg bag of frozen fillets, cut them into chicken nugget sizes toss in cajun spices and lemon juice and bake covered in foil. I then freeze in bags of about three. They defrost in the microwave in less than a minute.
jacket potatoes are a good one loaded with cottage cheese, prawns, smoked salmon, baked beans.
Scrambled eggs on wholemeal bread, baked beans on wholemeal toast, all day breakfast using bacon medalions, chopped canned potatos, mushrooms, tomato, egg.
I do a very simple pasta sauce that i freeze consisting of onion, garlic, passata, herbs, veg stock. Cooked to thicken. Sometimes i serve it with a good pinch of chilli but its easy to defrost and toss some pasta in for a light near instant filling meal.