When you've had real bread, most mass produced GF bread is like eating a slice of cardboard in comparison. So sandwiches became very hard for me to replace. I often have things like corn thins or rice cakes with sandwich toppings instead. Sometimes corn tortilla or buckwheat wraps (just make sure there's no wheat flour used). These are not too bad done in a sandwich press.
But I'd also recommend shopping around various local bakeries to find a GF bread that is edible or baking it yourself. Expensive but edible. Just be wary if you are coeliac rather than simply intolerant, that bakery bread may have some level of contamination. Eg, the bakery I go to slices the GF bread on the same slicer as "regular" bread but wipes it down prior to use. It cooks its GF bread in a separate oven and has a separate area for prep. This is fine for me but not for everyone.
I second the salads option. I would prep five salads on a Sunday evening. Varied them up week to week. Anything that might be liquidy (officially now a word) would go into a separate container and added immediately prior to stop it spoiling the salads for later in the week.
Occasionally in winter I'd run with a thermos full of homemade broth which I'd pour over rice noodles, veggies and a protein. Or, if I had access to a microwave, broth could be frozen into portions. (Just be careful, some producers add wheat starch to rice noodles so make sure they are definitely GF)
Also, not the question you asked, but I wish someone told me the following when I first had to go GF...
Get an understanding of what level of "tolerance" you have and what "casual contamination" levels are acceptable. For example, my mother, who is also GF, has her own toaster and keeps her own tubs of butter/condiments/spreads in the fridge/pantry. NO ONE is allowed to use them except her because even the smallest amount of cross-contamination can lead to a significant reaction. I'm not at that extreme, but that's something I wouldn't have thought of in the early stages.
Finally, read the ingredients of any "regular" foods you have. There are foods that contain gluten that I never appreciated. Some of the things that surprised me included ice cream, some custards, corn flakes, candy/sweets, soy sauce, pringles and lots of deli meats. It's not just the obvious breads, beer, cakes and biscuits. Also, as well as checking your food, check your medication - as horrifying as it sounds, not all medication is gluten free.