OP I am really sorry you are so ill and hope you will be better soon.
Please sit your dh down and explain that you are ill and about to be hospitalized. Lunches/bags/uniforms is all now his domain.
IF he feels he needs some help with anything you could write a few notes to help him find his arse in the dark.
IF he is worried and genuinely needs some assistance his mum could maybe come over and assist.
I think for the kids benefit they should not miss school, it would make life very hard for them and for their benefit they should go in. (NO real interest in what school thinks about anything personally unless they are about to do their GCSE or A-levels).
But I agree with Bill, "...at the moment getting your children's immediate needs met is the most important thing, and that may well mean them being at his mother's."
Pesonally unless you will be hooked up to machines or looking very ill, I would allow the children to visit and this is where your dh's mum (grandma) can really come in to good use in looking after whichever children are not going to see you. Of course if you or they find it too distressing then do what suits YOU.
I'd tell my dh I didn't mind take away meals, if you can afford it, or some late nights if necessary but they are his kids and he is now in charge.
The fact you have not pushed the lunches in his face shows you are a woman of calm nerves.
Get well soon. You will get through this and so will he, remind him you are the one who is ill, you need time, rest, help and care. He needs to step up. And fucking fast.
MamaOfBabas please do not blame the OP for her husband's failings, he is not a child.
OP please ask him to get counselling/therapy/assertiveness training or simply do a parenting course as soon as you are well enough. Whatever reasons or excuses he has for not looking after his own kids are not valid unless he has tried and tried and tried to work through any issues he has.