This is going to be a hard one to figure out.
Definitely you guys are going to have to make some decisions, and implement some routines to help make any transitions easier. First, poor pooped out dear husband is going to have to suck it up and not collapse when he walks through the door. Assign a few chores to the 8 year old and 7 year old - like dusting, vacuuming, loading and unloading the dishwasher, folding their own laundry, etc.
You're going to have to make peace with imperfection too. Just because the 8 year old dusts differently than you doesn't exactly make it wrong, it's just different - so you'll need to explain how you want it done in a way that it gets done (even though it may not be as good as you would have done it).
Start working smarter instead of harder. You may not be able to have THursday's be "laundry day" anymore...start doing 2-3 loads of laundry a day.
Sam's Club has a "click-n-pull" service where you can order stuff online (paper plates, paper towels, peanut butter, cheese, plastic cups, TP, etc.) and they'll actually go around the place and put it all in a cart for you; all you have to do is tell them when you'll be there to pick it up - the cart will be ready, so all you have to do is go pay. (You can order refridgerated stuff, and they'll send someone back to the cooler to get it for you too!)
You can find places to work that you can get the hours you want...it may not be doing what you want though. If you guys have decided that you can only work when your husband is home to watch the kids because you can't afford daycare, realize that's going to severely limit your options, but there are still options. Any of the 24 hour pharmacy/stores (like CVS or Walgreens), grocery stores/Wal-Mart's, gas stations, fast food restaurants, hotels (night accounting clerk?)....it's definitely going to be a case of you're going to have to decide exactly what you're willing to do to make money.
It might be a longshot, but it might be worth contacting a temp agency and asking if they ever have any inquiries for the type of thing you're looking for, and sign up with them. You never know.
Yes, whatever job you find will somewhat dictate what sort of schedule you are able to follow, but you'll have to give up some of your duties, and dear husband and kids will have to help pick up the slack. It is what it is. Everyone's going to need to be on board because you're doing it for the greater good of the family.
For what it's worth, and good luck!