My list (written from bitter experience): foil, cling film, bin bags, sugar, flour, eggs, baking powder, unsalted butter, quick yeast, bread flour, porridge oats, baked beans, mayonnaise, olive oil, sea salt (I can’t live without it), batteries, cellotape, washing up liquid, washing powder, tea, coffee, paracetamol, tampons, kitchen towels, toilet paper, Dettol spray, soap, pasta, pack of cheddar, jar of strawberry or apricot jam, lemons, apples, green bananas, DD’s usual cough and cold medicines.
I also make sure we have pack of petit pois, chips, and a few fish portions in the freezer.
We were unwell quite a few times over Christmas and having basics in stock was very helpful, not having some of them (e.g my tea) was a real pain in the arse.