Pasta would be good do either tomato sauce, pesto or cream cheese. Add a selection of bacon, softened peppers, onions, courgette, mushrooms etc. plus cheese. Everyone can make their own, it can be veggie (could add some chicken for meat eaters) and can be served separate. Pair with some garlic bread or salad.
Shepherdess pie - a mix of butter beans, grated carrot and courgette, peppers, onions, red lentils and sweetcorn in a tomato sauce (a bit like shepherds pie). Top with mash - maybe serve it separately so this covers all the bases. Let me know if you want the recipe.
Omelettes - either normal or bakers omelette. Fillings can be varied for meat/veggie and would be gluten free. Can add salad or baked beans.
Sausages, mash and veg. Get some veggie sausages and just check the packet for gluten free ones, a lot more a fine to eat now.
Is fish an option? Or maybe a roast dinner at weekends with a quorn substitute?
Vegetable stir fry with rice noodles? Add chicken, pork or beef for the meat eaters. Just be careful with soy sauce for Coeliac