My partner and I wobble along the line of preppers, his parents too and as we holiday with them we end up taking quite a lot but we drive rather than fly as it's only 1h between where the in-laws are and the Euro tunnel
Toilet roll, kitchen roll, washing powder. dishwasher tablets, bin bags, coffee, tea bags, olive oil, tin foil, cling film, tupperware/lunchbox, reusable coffee cups and water bottle.
My daughter has a lot of food allergies so we also bring oat milk, oat yoghurt, vegan mayo, margarine, baking block and stock cubes. We had a birthday whilst a way so we also brought a cake tin this year as well as vanilla essence - flour & sugar etc we bought here
Medical stuff- 3 first aid kits 1 in each car plus one in a rucksack. Paracetamol, ibuprofen and antihistamines, treatment for diarrhoea, glucose and oral dehydration tablets, insect repellents and bite treatments.
Car stuff - spare bulbs, fuses. oil, washer fluid and water, decent jack and socket set, hi Vis jackets.
Portable cupboard light in case of poorly positioned light switches in bedrooms, baby monitors in case we are further from bedrooms than at home.
Bluetooth speaker for my daughter to have audiobooks in the evening.