I would write down all the big things that you think he will forget, and I would also make a list of easy dinners that he could make just so that in the moment when (if) he gets overwhelmed he can revert back to that list and pick something off of it. It makes all the difference let me tell you. Post it on the fridge.
You could write a list of whatever together too so that you both are on the same page and feel ready and organized.
If it were me, and the hubs wouldn't accept help then I would have a good friend pop by a few days into recovery just to "see" how things are going and offer any help. I would have her bring a casserole or something easy for dinner. It will help, and even if he says he doesn't want the help now, he might feel differently in a few days.
When someone watches J, I always cut up fruits and veggies, and little meats and cheese, just things that I know he will eat for sure and put them all on the top shelf in the fridge so that they can just grab and eat. I also make a few Pb and J's in there too, along with juice boxes or water bottles etc. Whatever the girls favorites. That will help Dad out a lot.
When I had my surgery I also put all my comfy clothes that I wanted to wear in one drawer so that hubby knew where they were too when I needed to change.
Try not to stress, you have 3 more days to figure all this out.
Tell him that you really think it's good to have back up and someone can be or will be by every few days to check in just because and that he can just deal! ;)
Remind him that you know that he can handle it all but that you are worried that he will run himself ragged and then what? You need him to take care of himself too. And that EVERYONE needs a break every now and then. So just stop being a man and let someone help!
Everything will be fine, and somehow you will all manage and all this will be over before you know it, and you will be better! And no more migraines! Yay!