when I go on a self catering holiday, I start a box about 3 or 4 weeks before I go, and fill it with essentials. Tea, coffee and sugar. Roll of kitchen towel and a box of foil. Cereals if you have them for breakfast. A small bottle of tomato ketchup and a jar of pickle, tins of soup and baked beans................the list is endless. Whatever you think you might be eating.
If you collect these things over a few weeks then you don't have to buy them all in one go.
Don't forget washing up liquid and tea towels as these are not generally supplied.