I don't eat gf anymore, but for a while I did when other health problems suggested coeliac. A usual meal plan for a week would be-
Breakfast-scrambled egg with chives
Lunch- jacket potato with beans
Tea- roast chicken dinner without gravy
Breakfast- smoked salmon and a poached egg
Lunch- chicken salad
Tea-chicken risotto with leftover roast
Breakfast- fruit salad and a smoothie
Lunch- omelette/frittata
Tea- aubergine parmigiana
Breakfast- eggs again
Lunch- quinoa with roast peppers and veg
Tea- salmon with new potato and veg
Breakfast- fruit or eggs
Lunch- halved roasted red pepper filled with new potatoes , green beans and a small amount of cheese.
Tea- chilli and rice
Breakfast- eggs on Cocotte
Lunch- new potato and ham salad
Tea- lamb tagine with quinoa.
Breakfast- fruit or eggs
Lunch- aubergine boat with cheese and spices
Tea- pork and prawn meatballs in a spicy chicken broth with rice noodles and bakchoi
Generally I ate rice dishes-fried rice, paella, multigawny soup, etc. and roasts featured more frequently than otherwise. rice noodles are readily available and delicious.
I didn't use substitutes- at the time they were expensiv. as you can see breakfast was a bit egg focused (though I keep chickens so that's a factor)
But it is an achievable if slightly restrictive diet. Hardest as you have anticipated is eating out. I felt limited to chain places where they advertise gf on the menu. And at the time coffee shops were pointless, though reading other replies I see this is no longer the case
More and more places are catering to gf, it's much easier now than it used to be. Good luck.