There are certain items I always make sure I have in and replace whenever we run out so that I can always make a meal. So at any point I can do:
Beans and/or egg on toast. I always keep a loaf of bread in the freezer and you can toast slices straight from frozen.
Jacket potatoes (I bake entire bags at a time and keep them in the freezer then heat up in the microwave). With cheese, beans or tuna mayo.
Vegetable risotto (arborio rice, frozen veg, stock, vermouth and some form of butter and cheese to stir through at the end.)
Vegetarian stir fry noodles (egg noodles and frozen veg plus a sauce made from soy sauce, crunchy peanut butter, chilli flakes and honey.)
Various pasta dishes as I keep packets of dried pasta in the cupboard and jars of pesto or I can make some form of sauce to go with it e.g garlic, chilli and olive oil or butter and marmite (Nigella recipe) or egg, grated cheese and pasta water for quick carbonara.
I can normally knock up a curry as always have tins of chickpeas and chunks of frozen butternut squash or cauliflower, plus a spice paste and stock cubes. And always have dried rice in the cupboard.