Hi Op. Sorry I have not read the whole tread yet - will do so when I have a little more time. So forgive me if some of these ideas have been mentioned already!
None of your foods are the work of the devil and you could make some easy changes to them. Everything below should be easily purchased in your local supermarket and not hard work involving loads of prep and special ingredients.
Instead of frozen pizza why not get fresh pizza bases, buy some tomato sauce (long term you can make your own pizza bases and tomato sauce easy as pie) get loads of different things - ham, cooked chicken, tuna, sweet corn, sliced onions, peppers, mushrooms etc. etc. and cheese of course and have a make your own pizza night with the kids. Let them pick the things to put on the pizza´s and try and them put them in the oven and cook eat and enjoy. Go for the thin bases not the deep pan and they are pretty healthy.
Instead of fish fingers - do your own battered fish, or fish cakes (fish, mash potatoes, eggs, seasoning)
Baked beans are pretty ok to be honest. But why not do a jacket potato night? Same as the pizza night cook jacket potatoes in the oven. Get loads of bits and pieces, tuna, cheese, soft cheese, baked beans, home made coleslaw etc and lets the kids fill there own potatoes. Favourites in this house, "tuna and sweet corn with mayo" "tuna, baked beans and cheese" "chicken bacon and sweet corn with mayo" home made coleslaw.
Breaded chicken - could be chicken stripes. Get chicken breast and cut long ways into slices, dip in flour, egg and then breadcrumbs and bake in the oven. Great healthy food.
Sandwiches, golly there are sooo many things try the same things as for make your own pizza nights and some of the potatoes ides too, meat ball subs are a total hit here made with left over meatballs and tomato sauce from spaghetti and meat balls and rolls instead of bread
Breakfast - dippy eggs (eggs are great!) with soldiers as Dad is in the army, Fruit smoothies - plain yogurt, bit of milk and frozen berries or fresh, Banana pancakes
Snack ideas - fruit sticks (take sticks and put on chunks of fruit, grapes etc serve), Sliced veggies and dips (carrot sticks, apple slices or sticks are good to start with) and a variety of dips (humus, mayo, soft cheese etc) Plain popcorn,
The squash - just reduce the amount you put into the glass etc week so it gets weaker and weaker eventually just plain water.
Pudding does not need to be served every day save it for treat nights.
If the weather is good with you get the BBQ out! Cook chicken thighs, pork chops, good quality sausages, make some coleslaw - bung a hand full of raisins in as it tastes a bit sweet then do jacket potatoes on the BBQ.
The winter is easier to be honest to get veg etc. into kids but start making the changes now and you will be set for a winter of pasta dishes, baked dishes, and one pot meals!
You can do it op.