A few of my favourite ideas are a simple pasta (pasta, bottled puree and grated cheese), a basic tofu stir fry (diced vegies and tofu in a tomato and peanut butter satay sauce) or a simple fresh sald, with your favourite vegies and some cheese, canned beans or pasta to provide some extra bulk.
When we arrive home late at night from our Melbourne trips (which seem to take 7/8 hours door to door) & our local supermarket has run out of takeaway chickens, I open a can of baked beans pour them into a container, & heat it up in the microwave. I also cook a fried egg & bacon to put on top. I doesn't sound very exciting, but we like it! You can also ad a teaspoon of maple syrup or chopped parsley, & we eat it on a slice of light rye toast, (or normal toast, if you'd rather of cause)