I have only skim-read through a lot of the posts since my own a few pages . However, I just had to come back on this from a pp.
^The average family meal will set you back at least £5 and that's without desserts, snacks, odd bits of toast here and there, ketchup / mayo. Even a pack of ham with five slices costs £1.50 so lunches must be at least £1.50 per day per child by the time you've added the fruit and snacks - unless you are reeeeally careful. Then there's juice, milk, tea and coffee. And breakfast.
Even if you do breakfast and lunch for £2 per person which would be fairly grim, that's £56 a week. A spartan evening meal will add £35 and there would be no cleaning or toiletries allowed. If you include those you can't manage for less than £100.^
To tackle a few of the points: my DS rarely has ham in his sandwiches, unless I buy deli ham at the reduced counter, when I can typically get about 5 large slices of naice ham for around 50p. I generally slice it in half, so have 10 portions at 5p/portion. At other times, DS has Marmite, jam, paste or cheese spread sandwiches, which are all pennies for a small smear used on a sandwich. He has a fruit puree pouch at about 20p, a choc biscuit bar (Tesco value, 6p each), Tesco value apple juice (15p) & a pot of cheese & cucumber (probably about 20p worth). Bread is always yellow label & the most expensive I will buy is 80p/loaf, so 2 slices is probably 16p max So, his packed lunch costs an average of 82p per day.
For breakfast, we either have Sainsbury's Basics cornflakes (very tasty even according to FIL who will otherwise only eat Kellogg's), which are around 30p for a bag that lasts us a school week if we all eat just those (so 6p per day for 2 adults, 2 DC under 5) or we have porridge made with Tesco Value oats, which are 75p/kilo, that bag lasts us 2 weeks if eaten exclusively. Sometimes, I will see treats in the bakery section & we'll have those instead, usually at the weekend. Today I got 2 packs of 2 Tesco Finest Pain au Chocolat for 30p/pack, a pack of 4 croissants for 36p, 2 packs of 6 crumpets for 26p/pack. These will be eaten with hm jam made with foraged fruit, so again this is very cheap. Add the cost of juice (2 cartons of juice on offer for £1, 1 carton lasts 1 week as we water it down for the boys to make it less sugary), tea (Sainsbury's Basics, highly recommended, approx 30p for 80), coffee (Grand Mere filter coffee bought in France, I think 5 Euros for 4 blocks of coffee) & milk at £1 for 4 pints and I am pretty sure you have a tasty breakfast for 50p per person or less. So total breakfast & lunch cost for 1 person, approx £1.32/day.
Dinners can equally be done cheaply with good shopping, again I buy largely reduced items. Tonight I got 2 packs of fish pie mix for £2.60, as well as a chicken pie for 80p. Each represents at least 1 main meal for the whole family & will be accompanied by fresh reduced price veg & full priced potatoes, so I would estimate the cost to be around £3 total for 2 adults, 2 DC. It just requires a bit more time & effort. I know people will say that you cannot rely on reduced-price items, but I have always been able to buy any fresh items I require for less than half price, as I have found out the times items are reduced & made the effort to go along then, once or twice a month is sufficient to stock up for a whole month, usually.