PersipanI would suggest getting lots of things to add flavour, like herbs & spices, stock cubes, etc - stock up on them now, and you probably won't need to buy them again for ages. So, for instance, salt, peppercorns (and a pepper mill), Italian herbs like oregano and thyme, chilli powder, dried chillies, stock cubes/powder, worcestershire sauce, tabasco, soy sauce, sweet chilli sauce, ketchup, curry paste, tomato puree, cinnamon sticks, cloves, those kinds of things - the specifics will obviously depend on the kind of food you like to eat. Also get stuff like jars of jam, peanut butter, marmite, whatever it is you like on toast, really.
Then, stock up on stuff you can store. Tins (tuna, tomatoes, beans, soup - condensed soup is great because you can also use it to make sauces, tinned fruit), cereal, pasta, rice, noodles, sauces (pesto, curry sauce).
Get some fresh suff, but remember it won't last forever, so don't go mad. Fruit and veg, meat & fish if you eat them, eggs, dairy stuff like cheese. Have some idea of what you plan to make with fresh stuff, or it'll all just fester in the fridge. Also, maybe get some frozen stuff, but you may not have all that much freezer space.
Also make sure you get the basic essentials like teabags, coffee, sugar, milk, bread, butter, garlic, cooking oil, biscuits, maybe some snacky things.
The plan, ideally, would be to come away with everything you need to make meals for a few days, and then the basis of a storecupboard you can dip into to jazz up a meal made of basic ingredients as time goes on. (So, you could buy some peppers and onions and make a pasta sauce from them using a tin of tomatoes and some garlic and herbs and dried chilli, for instance).