You could try to plan your meals based around the carb and take it from there. 2 x rice, 2x pasta, 2 x potato, 1 x bread based meals a week in the evening. Also try to use dried beans and pulses a couple of times a week.
For instance:
mediterranean beans and rice
chicken risotto, salad (1 chicken leg, finely chopped)
chicken and mushroom pasta bake, greens (other chicken leg, finely chopped)
tomato and herb pasta with cheese, salad
bean chilli with jacket potatoes
new potato and smoked mackerel salad, crusty bread
cheese and cherry tomato bread pudding, carrots, cabbage.
USe the chicken carcass to make stock for soup at lunchtimes and the rest of the meat for lunchtime sandwiches (coronation chicken) and filo parcels (with mushrooms, onion and a little white sauce. Cook a 1lb bag of dried beans, use half for the med beans and rice and the other 1/2 mixed with a tin of kidney beans for the chilli. Buy a big baguette, eat half with the mackerel and use the other half for the bread pudding.
For sweet treats, bake some oat and raisin cookies or some drop scones. Kids can take these in packed lunches as well.
Another way of saving money is to buy and cook a roast at the start of the week, strip the meat off it and divide it between 3 or 4 meals for the week. Then, if the roast has bones, boil them for stock for lunchtime soup.
You could buy a large pork roast and then make:
macaroni cheese with pork and peas or broccoli mixed through (4oz, finely chopped is enough)
savoury rice with pork and veggies (again 4-6oz is enough)
shredded pork in barbecue sauce in rolls or tortillas with corn on the cob and coleslaw (3oz or so a person is enough for this)
pork rissoles made with 1/2lb meat, 1lb mashed potatoes and 1lb mashed veg, a couple of spoonfuls of stock or sauce to bind and then roll them in oatmeal.
Any meat still left over could go into sandwiches, pasties or couscous salads for lunch.
fill the gaps with:
lentil and potato curry
lentil loaf, wedges and salad or lentil soup with bread
smoked mackerel chowder and bread or jacket potatoes with smoked mackerel and braised leeks.
For lunch you could boost the fish oils by mashing 1/2lb smoked mackerel into a tub of philly type cheese with some lemon juice and black pepper. Use it as a sandwich spread. Another good way of getting EFAs into kids is to make a nut and seed butter for sandwiches. 400gms salted peanuts, a couple of handfuls of seeds (I use linseed and sunflower) and about 100mls sunflower oil, blitz together until smooth and spreadable.
To add a bit of variety you could make spinach frittata, or similar, chill it overnight and send wedges of that for lunch with bread and butter and perhaps cherry toms and cucumber. 6 eggs would make enough for 4.
Lentil pate is good for sandwiches or crispbreads for lunch. 1 cup red lentils, 1 large chopped onion, 2 cups veg stock, garlic and black pepper, simmer together until lentils are soft and liquid is absorbed. Beat in enough veg oil to give a spreadable consistency and kind of smooth texture.
To keep your costs down it is important to plan your meals and make the best use of resources, hence stripping joints and making into various meals and buying multi purpose ingredients like packs of smoked mackerel, bags of lentils and large baguettes. Doing it that way means that you don't have to go down the value ham route and that everyone's nutritional needs are met while you still get a good variety of different meals.
Try eating porridge or homemade oat and raisin bars for breakfast. Cheap, filling and full of B vitamins. Also HM pancakes with chopped bananas and a spoonful of yoghurt makes a good, cheap breakfast.
Try not to obsess over things like 5 a day, it's better to take a longer view and look at what your eating over a week or even 2 weeks. If things balance out that way, then all is well.
Hope this helps a bit. It's had feeding the family a decent diet on a small amount of money.