HandbagCrab,
One day a week, make a double batch of a dinner and freeze the second half. Spag bol, curry, chilli, lasagne, shepherd's pie, stews etc. all freeze well. If possible, try to do this dinner the night before (after frantic arrival and dinner period, when things are more relaxed - preferably with a glass of wine in hand and tv on), so you only have to turn on pots/oven to heat things up (maybe boil some pasta/rice/potatoes too) when you get in from work. I tend to do this on Sundays for Monday - as I am cooking a Sunday roast in the afternoon anyway.
Yes, yes to quick dinners. Scrambled eggs or beans on toast, fried egg and rasher, salad etc are all acceptable once a week too as fast options for particularly busy nights (make sure a full lunch box that day, and have a pudding or few biscuits ready for later if bigger appetites need more). Keep a few things like tinned spaghetti, beans, tuna etc on hand to rustle up something fast and nutricious (ish). Decent fish fingers, or proper chicken goujons are good freezer standbys too, along with a bag of frozen peas/sweetcorn/mixed veg, and oven chips. Another night of turning things on and getting on with something else while it cooks.
After dinner, when cleaning up, try to peel veg or prep stuff for tomorrow's dinner. And make any lunches needed and put into fridge for morning. Lay out tomorrow's clothes when putting kids and yourself to bed. Pack bags before retiring too (anything you need, does DC need changes of clothes for creche etc?).
Kids go through loads of changes in creche. Not always one per day, but sometimes more than one (and I don't think I ever had a week with less than 2). So between having enough changes to put on every morning, and keep the creche cubby hole stocked with emergency changes - washing can mount up fast. So aim for LOTS of easily cleaned tracksuits that are comfy, and plain tops to go with a few different bottoms. Lots of socks and vests. Keep the pretty outfits for the weekends. I don't mean it all has to be plain - just things that will match up together and can all be washed together. And bulk buy so that you can run through 10 outfits between mon-thurs and not have to panic about washing one for fri.
Run the washing machine regularly. Try to set it up to run while you are out, if yours allows that. So sort the clothes when you are doing the organising after dinner, but set it to wash in the quiet time next day (rather than distracting from the 1 programme you WANTED to watch!). Chuck it on the line/clotheshorse/into tumbedryer as you get a chance when you get in/after dinner. Put the dry clothes into a basket of clean things that you can rummage through if you need them, but do a sort/fold job once a week on that basket, and ironing after that. The most important MID-week task is getting things clean and dry.
I tend to have a slightly "bulk options" wardrobe for me too - somewhat capsule in the sense that lots of my tops are plain and can go with about 3/4 different suits each, and a good few plain black trousers - but plenty of things that I can grab on the go and not panic about me having clean things.
I'm sure others will have great ideas too so I'll stop before this becomes a thesis.