Bring a few key things with you - handful dishwasher tablets, favourite seasonings or new bottle of any sauce DCs always use etc.
Find a decent sized shop when you get there rather than always using the corner shop, and get all the basics there. As part of that, get a fair bit of lovely fresh fruit, ice pops for the freezer, the makings of 1 family favourite and 1 other dinner based on local seasonal ingredients, but also treats for snacks, breakfast bits, tea/coffee, squash etc. Wine or beer for grownups. Maybe ham and cheese (insert your family favourite fillings here) for sandwiches or some salad bits for lunches. Maybe get some cans, multipack crisps, fruit, sandwich bags in the big shop - to be able to make picnics for the beach or day trips, so stops on the way are for ice cream or a cold drink rather than full meals.
You’ll probably find a local bakery for morning croissants or french sticks. Have some lovely jam from the shop to go with it.
Don’t be afraid to have some meals out - it’s about choosing how much to eat out, what meals, and making the meals you cater nice ones but easy for shared preparation. Get the DCs involved in some. DH definitely does some. It’s a holiday for everyone.
I like to bring a handful of ziploc bags and seasoning to marinade chicken to throw on the bbq to have with easy fresh salads and crusty bread. Or make things that can cook in the oven with minimal prep (like big chunks of vegetables roasted with baby potatoes and some steak or lamb or chicken or fish). While I relax with wine and olives or crisps on the terrace, maybe playing games with DD or just chatting with DH. It’s not about slaving in a different kitchen.
And you need some treats or you will resent it. We tend to eat out for 1 meal a day when away like that (and it is a mix of breakfast, lunch or dinner during the week).
Researxh the area beforehand, are there nice beaches for swimming or exploring, interesting walks, good museums (some have entry fees), historical sites, things that are free or cheap to do, as well as any paid activities. So you might go 1 day to the splash park but swimming at the beach 4/5 days and plan to get to a couple of nearby places by hire car or local bus another couple of days.
bring backpacks (school bags are fine) to bring picnics and swim gear, and allow you to pick up interesting bits while you are out. And bring your refillable water bottles to keep hydrated when out - but do make a stop for a cold beer/fizzy drink stop at the end of the walk as well.
I find the initial shop can be expensive (we often drop €200-300 on that), but then we don’t need all that much more in the week food wise except for daily bread, and some meals out/treats/couple of paid activities.