Lots of stuff has already been mentioned.
I had 4 years when DH was away for 2 weeks (from lunchtime Sunday, until lunchtime Saturday 14 days later), and home the other 2 weeks (and under pressure to go see ILs on the only weekend per month that he was totally at home), and sometimes having longer trips (only 2 hours difference but 11 hours flying away).
At that time, what saved me was an au pair - but only because DD was small and I had a FT job an hour's commute away, so childcare was problematic (there was no pre-school option at the time so I could only drop her at 8.20, but needed to be at work before 9, an hour away). Au pair used to get DD up (if she wasn't before I left) and to school, and collect her from afterschool twice a week. And she did some cleaning. But we kept the afterschool club, and DD still kept up a few afterschool activities (swimming one evening, and a different sports club on Saturdays).
But organization is key. And being aware that there is likely to be a:
Routine for when DH is at home with you, and
A slightly different routine for when DH is away.
(For numerous reasons!).
Have plenty of sets of uniform for everyone and of other clothes, so that you don't have midweek crises of dirty laundry.
In our case, I insist on a clean shirt daily so I have 6 shirts, and we have a spare jumper, but only 1 skirt (it's washed weekly, but expensive and doesn't tend to get too bad).
I also have 3 full sets of PE gear, as DD has training 5 days per week - I'm not forking out for a full 5 as that is expensive! But I try to get Monday's off her on Monday night to add to a load, so it's clean for Friday.
I have a similar approach to DH and my clothes - we should have sufficient clothes to not need items from laundry, on a regular basis at least, during the week.
My other thing about laundry is to wash regularly, but only fold once a week.
So I will do a load most days - I tend to sort it from the hamper either late at night, or as I go down in the morning, and set it up in the machine to be done as we get home from work in the evening (it runs sometime during the day). If the weather will be good for outdoor drying, I may try to have it done for early morning when we are getting up.
It can go on the line outside, the clothes horse indoors (we have a dehumidifier) or the tumble dryer as necessary. But I throw everything that is dry into a clean laundry hamper downstairs during the week - people can rummage through that if they need something urgently.
On a Friday evening, or Saturday afternoon, or even Sunday if time is against us, I sit down to fold everything in the clean hamper - in the sitting room, in front of the tv with DD, so it doesn't feel like such a chore. She will do some, but it's as much about shared time together.
In our house, DH took over all ironing when DD was born (and there's not much of mine) so that tends to wait until he is home. He usually does that on Sunday nights (watching CountryFile with us buzzing around the kitchen doing our jobs, and all together).
Every night when going to bed, I make sure the kitchen is clean, the breakfast things are laid out (glasses, bowls, cutlery, cereal boxes etc), and that lunches/dinner are organized for the following day.
DD used to want hot lunches - so it was leaving the kettle ready to boil with pasta in a pot, and her flask ready to heat and add cooked pasta to. But I make my own salads and have them in a box in the fridge (I usually do 2 days together as that works for me and I get a night off in between), and it used to work well for sandwiches too.
Dinner means knowing what I am doing. And as much prep as possible done for it - chicken already diced and put back in a Tupperware in the fridge; vegetables and potatoes peeled and chopped and left soaking in water or in a Tupperware or marinating in a freezer bag if they are needed; knowing I have enough pasta/rice in the cupboard; getting anything out of the freezer to defrost (and set up in the oven on a timer if that's an option - lasagna, cottage pie, etc - so it is cooked as we get in the door or just after that).
It is much easier, I find, to get in the door and lash into cooking something already prepped, when DD is starving and grumpy and needs to get homework done, than starting everything then.
And later, after dinner, when I am tidying anyway, it's as easy to prep things a little calmer and just add any extra implements to the washing up that I will be doing anyway.
I also keep cheats in the cupboard.
A few meals I can make from just storecupboard ingredients - onion, garlic, tinned tuna, tinned corn, couscous, rice, pasta, tinned tomatoes etc.
Bacon lardons (lidl do handy packs which are great for fast cooking) and has a long life in the fridge, as does Chorizo. And eggs.
And while I prefer to cook from scratch as much as possible, I keep a bag of frozen petits pois peas and a couple of good jars of sauce (some tomato for pasta, and some curry) in the cupboard to do shortcuts on some nights.
And some nights, cheese on toast is enough!
I try and coordinate the weekly diary with dinner planning - some nights are chaos as there are activities in the evenings and we need faster meals, while other nights have no activities and I can either make slower dinners and/or prep ahead for the following night. And I also need to try and see what nights we need big meals, and what nights people only need more snacky meals (as they've had a larger meal earlier, or no sports that day etc).
I try to do larger batches of meals that can be frozen, when I have more time. So I used to do those on Sunday afternoons when I was cooking a roast dinner anyway - spaghetti bolognaise, chilli, lasagna, cottage pie, smoked fish and broccoli pie, various curries etc. Nowadays, it's more likely a midweek night, but I can often find a night within a 2-3 week period when I have time to do a large batch (2-3 dinners worth) of sauce/dinner the night before we eat it, and just reheat the sauce and cook pasta/rice/boil potatoes when we get in - or I might get an odd day to blitz the kitchen on purpose (annual leave, a particularly quiet weekend day etc). Any night I make Mac'n'cheese (as I include bacon and loads of veggies) which is a "cook as I get home from work" dinner, I do a large pot and freeze the leftovers, to reheat as pasta bake.
If you do get time to do a blitz, it can be handy to spend some time even prepping ingredients for the freezer - so chopping chicken into dice and bagging into 1 dinner portions, chopping veggies into dice (and marinating if you want) so they are ready to pour onto a baking tray in the morning for a 20 minute roasting for dinner, doing the slow fry of diced onions and garlic to have the base of a curry/tomato sauce, or even making a tomato sauce and freezing that in portions (great for teens to make their own snacks!).
Snack foods are also important I find - DD comes in starving, and hence, vile, until she has something solid to eat. So it used to be things like raisins and fruit, now its more breadsticks, cheese, pesto/hummus for dipping, sometimes I will have veggie sticks cut in a tub in the fridge, cherry tomatoes are good, ...and varying those so she doesn't get bored of any one. And she's making her own smoothies, so fresh fruit is good (but frozen fruit more practical - I try and have a bag of frozen always) and apple juice.
I have a list on the fridge door - I try to mark it as things are getting low, but there is a rule that if anyone finishes anything, they MUST write it up (or I won't know we need more). I tend to try and have extras bought ahead of time anyway, but not always. But I won't know if DH needs shaving cream, or DD needs deodorant, unless they tell me (by writing it up).
Online shopping, if you can, does help, once you have it set up initially, it's often fine to do on a commute (if not driving) or while you eat lunch at work.
Online banking is also really useful, especially if you can set up bills to be paid on specific dates - do it the day they arrive but set them up for their due date or pay date or whatever date suits you.
YYYY to keeping a family diary and writing everything in as soon as you get it.
I keep envelopes in a drawer in the kitchen for notes to school or posting letters/paying bills etc, and a few stamps on the fridge door.
Emergency numbers are all on the notice board in the kitchen, along with a copy of DD's timetable, takeaway menus, etc. (We try to keep takeaways to a max of one per week - but there are weeks that we need the flexibility and we just try to not have them some other weeks to make up for that).
On cleaning and organizing.
Yes we do have a cleaner coming once a fortnight for a full clean, and that makes it much easier to keep it mostly under control in between that.
I keep a bottle of bathroom cleaner and bleach and a stack of cloths in the bathroom upstairs - so I can very quickly clean that bathroom in a few minutes regularly (we keep 1 colour cloths only for bathrooms, and any other colours can do kitchen/dusting/whatever else). Dirty cloth goes straight in the hamper once I am done to get washed. And I just bring up a few more from the kitchen cupboard (where all cloths go after washing) whenever I run out upstairs.
Sweep kitchen floor as needed, some nights its every night, other nights I can ignore it (autumn leaves and mud, summer cut grass on boots, etc tend to mean more sweeping). If I need to spot clean the kitchen floor, I have some wipes under the sink - rather than getting out the mop to do the whole floor. But if it needs a full mopping, I tend to do that in the evening after DD has gone to bed.
Bags for work and school are packed up at the end of the evening, ready for tomorrow morning. Including any sports gear needed, projects, notes to school/permissions slips/money etc.
Clothes for tomorrow are also laid out before bed - DD set her own system up this year (primary was non-uniform, new secondary is full uniform) where she hangs up 5 shirts on Sundays, with 5 pairs of socks and 5 sets of underwear, all ready for the week ahead. I only do mine for the following day - but I do have jewellery/accessories out and shoes picked out as part of that.
I try to leave downstairs clean and tidy as I go to bed. Put tables back in place, cushions back on seats, toys back in boxes, bins emptied if necessary.....decluttered and neat rather than cleaning.
And always have something in my hand when going up or downstairs anyway - to put it back in its right place if I can.