Sorry he's not well Weka xx
I'm sure that naturopath doesn't have a busy life with two small children and a weird diet to worry about!
If you look back probably on here but also maybe the health board, I have written about eg intolerance diets before (including re Missy I think), there should be some things of use.
It's always really hard when you have a list of what not to eat, so the first thing to do is make one of what is ok
Eg it sounds like meat, chicken, fish, almost all vegetables, peas/beans and lentils, fruit...eggs?
Then there are nut milks, coconut milk drinks (as milk I mean, not as in cooking in curries); rice also not excluded?
Rice cakes as well as rice milks etc.
Chickpea flour (aka gram flour), if potatoes allowed then potato flour, there's also rice flour...loads of Indian recipes using those, and lentils.
Make a start with what's definitely allowed then see what you can come up with.
But I also have to say. If it was you that was being advised to follow this diet, you'd be making all the food and meals you normally do for your husband and children as well as figuring out what to have yourself.
It would seem more than fair, if husband wants to get well, for him to work a lot of this out for himself, then you can feed you and the children and he can sort out his own. Some meals would easily overlap, especially main meals - chicken/meat and veg is pretty normal and if he's not allowed the gravy or whatever then tough
Certainly get him to investigate what he could make bread out of, and get on with it
Good luck xx