This is not a complete packing list. This list contains only the things that are not obvious, things you might not otherwise think about bringing, but that you'll appreciate having brought.
Bathrobe, for the trips between the house and the hot tub
Slippers/flip-flops/sandals, for the trips between the house and the hot tub
Bed linen. You already know, but it's so easy to forget.
Bed-wetting sheets. If the kids still have an accident once in a while.
Football
Pool toys
Beach toys
Board games
Video game console like fx a Nintendo Switch
Padel bats if you want to go to the nearby padel courts
Toilet paper
Hand soap for 3 bathrooms
Hand towels for 3 bathrooms
Cloth for wiping down wet surfaces
Tea-towels
Paper towels
Dishwasher tablets
Dish soap
Dish brush / sponge
Spices (salt & pepper, etc)
Cooking oil
Coffee and tea filters
Coals, fire starter and lighter for the barbecue
Laundry detergent
Vacuum cleaner robot – it's just so convenient to wake up to clean floors (there is a 'manual' vacuum cleaner in the house)
Cordless vacuum cleaner - there is a corded vacuum cleaner in the house, but the cordless ones are nice to have here and there.
Wagon of sorts for all the things you want to bring to the beach