OK I won't be the most helpful, but I will try.
I think, from what you say, you don't have any hob at all - just microwave and oven?
Do you need lunches as well, or just breakfasts/dinners and weekend lunches?
So 9 dinners, 6 of them solo and 3 of them with DCs?
9 breakfasts, 6 solo and 3 with DCs
2 weekend lunches, both with DCs
I am sort of seeing a few meals in your ingredients, but the no pots on a cooker is throwing most of those out on me.
If you have a kettle, couscous can be "cooked" using just boiling water (I can't see how to cook the spaghetti or rice).
I would be inclined to try and do 1 larger shop so that you can use the £3 voucher.
Tinned tuna could make one of those sauces and some pasta into a bake, perhaps with some sweetcorn, as 1 meal not needing fresh meat so next week.
Rashers or bacon lardons also tend to have longer life, or a piece of bacon. Perhaps bake a piece of bacon for dinner with the DCs over the weekend (cabbage is a cheap but good veg with this, or carrots, or the peas you have), leftovers for sandwiches for lunch, and to add to another pasta bake dinner or use in scrambled eggs or frittata type "dinner" omlette.
My immediate thoughts on very useful ingredients include eggs, cheese and either bread or a bag of flour (can make basic bread/scones/pancakes then - as well as the basic white sauce or to bake).
As well as regular milk, maybe 1 bottle of long life milk or powdered milk to last longer.
Sorry I am not much help - I will have a ponder....