I build in left overs. So if I make baked potato I'll add some extra and the following day make gnocchi (which is really quick).
If I make Yorkshire pudding then I do 2 x as much batter as I need and make pancakes the next day.
If you are having boiled potatoes and veg with something make extra and have bubble and squeak the next day.
Stir fry with noodles. Buy a pack or ready chopped veg, put oil in the pan or wok, add the veg and stir fry. Once cooked add a packet (or two) of noodles and some boiling water, stir for a couple of mins and add soy sauce and sesame oil. Serve.
Soup - I often make it in the slow cooker so I can use root veg and then use a blender / stick blender. You could chop veg the night before then just dump it in the sc while you have breakfast and then after work season and blend.
Things on toast, beans, cheese, sardines, eggs (fried or poached).
My mum used to make 'milk cheese on toast' - stick the bread in the toaster / under the grill, put a pan of milk on the hob and crumble cheese in to it, you need a crumbly cheese like Wensleydale it makes a sort of cheese sauce. Pu the toast on a plate and pour over.
There is nothing wrong with the odd tinned soup or tinned spaghetti on toast occasionally.
You can add lots of things to rice as it cooks, my favourite is smoked haddock with orange juice.
But you can add fresh or frozen veg, tinned tuna, chicken, chorizo, chopped hot dog sausages add some coconut milk or creamed coconut, tinned and rinsed kidney beans or chickpeas. You can put in herbs and spices to taste. If you kids are the adventurous type the seafood.
If you have a rice cooker all you do is throw the ingredients in, add water and leave it to do its thing.
Make too much rice and the following day make egg fried rice or peppers stuffed with rice.