When I broke my foot last year we had a tonne of home help through ACC for my jobs around the house. Which was heaps because I was SAHM to 3 kids haha! They should be able to cover all the jobs that your DH is solely responsible for. They will ask questions like, for example:
ACC: do you usually do the grocery shopping?
Injured: yes.
ACC: is there someone else who could do that?
Injured: yes, my wife could.
ACC: Ok no need for home help there then.
So it has to be something like, when I get home from work I usually look after the kids for an hour or so, while my wife gets dinner ready. Or, I usually do the dishes but my wife could do that if someone could look after the kids for her.
Call up ACC and see how you go