You cam make up sandwiches ahead of time and freeze them. That way they are still cool when he gets around to eating them.
I organized my kitchen, especially my refrigerator, so there is a special section for lunches and we follow a checklist.
So there is one cabinet dedicated to "snacks" - shelf stable food (like potato chips or cookies) in single serving container (pre-package them in baggies yourself) - that you can just grab-pack-and-go.
The frig has a similar set-up except it is a plastic box that acts like a drawer (although you can use one of the veggie bins in your frig if you want). It has veggies like tomatoes or carrots and fruit like grapes, apples and berries already portioned for lunch. I get up with my husband and make him breakfast so I make his lunch, too, so my bin has all the sandwich makings. I do have a separate bread bin but the lunch bin has condiments, luncheon meat, etc in it. I'll even sometimes bag-up leftovers for him to use as lunch later. If you decide to make sandwiches ahead and freeze them, just store them together in a small box in the freezer so you can keep tabs on your inventory.
I've gotten hubby's lunch down to a science. His lunch box is organized in such a way that everything has its place.