If you are buying lots of things to assemble - do you buy veg pre-prepared as well? Because I know on really bad nights, I will run into M&S for ready to cook stuff and pay over twice what I pay to get it un-prepped. But if I know the night before that it will be manic, I will peel and slice my onion and put that in a plastic tub, and the same with any other veggies (say diced peppers, peeled and sliced carrots in water, sliced courgettes, and a clove of garlic in with the onion to slice while onion cooks). I try to have the meat ready (sliced etc, and sometimes throw a marinade over it) in a freezer bag in the fridge - to just pour into the pan when ready. And a pouch/jar of sauce to pour over. Or a bag of frozen prawns and handful of frozen peas can be thrown in with a pouch of sauce if I have otherwise not prepared.
When DH cooks at the weekends, make enough to freeze a few spares and slowly build up a nice mix for DC.
While you are off, try to learn a few more things to cook yourself - but start with lunches and be your own guinea pig if you don't want to expose DH to it at the start. Maybe keep some pasta from the night before, and cook a rasher and some mushrooms, and make a carbonara or cream sauce to go with it (carbonara is so fast and easy, I only learned it recently but: mix together an egg and some cream, season generously (less salt if using bacon), and add a decent handful parmesan - cook pasta, drain (keeping a cup of boiling water to the side), pour in sauce mix, stir together allowing existing heat to "cook" it, use a few spoons of pasta water if it gets too thick, put the pot back on the heat if you need to cook it a little more just be careful to keep stirring and not get as far as "scrambled eggs" rather than sauce - chuck in your bacon/mushrooms, serve.)
Or a basic tomato sauce which can be the base of so many things - and if you freeze in flat freezer bags in portions of 1-2 cups, it defrosts in minutes. You can add seasonings, veggies and meat to it once defrosted to change it up a lot, making it Italian or Mexican, but quick and easy.
Mini bottles of wine are expensive - would the person they are for have the willpower to stop after the glass that's in them if it were a bigger bottle? Best would be a box, as while it's big, there's no air getting in so it lasts a long time even when opened. But a "normal" bottle, holding 3 mini-bottles, easily lasts a week if capped again and kept cool (fridge for white, just cool corner for red). And could save a bit.
Washing powder capsules is expensive, yes, but it depends on the space you have available. I know we only have a small shelf to take bio/nonbio/softener and the colourcatchers etc as well, so we use tablets/pouches. Just can't fit big boxes of powder. But I occasionally use the bottle of liquid detergent instead, and at least that I can reduce the amount in a wash where clothes are not so dirty.
The same for cleaning things, washing up liquid, toilet rolls etc. Many of the lesser brands are fine, and while I still use Fairy for dishes as it does seem to work best for grease, I use own brand (but the luxury version) toilet roll which is quite a bit cheaper. You don't necessarily have to go from the top priced brands and options to the absolute basic to make pretty decent savings - just drop one level at a time until you decide that, nope, I think the 1 step up from this is the level we want to stay at.