Can only repeat whats been said. A quality colbox like the Coleman Xtreme will work wonders, but only in UK temperatures really as it works on ambient temperatures. If France or maybe even a warm South England it can be difficult. Also it can get a bit annoying to make daily trips to the site freezer and maybe discover that someone else has "borrowed" your ice packs. Once or twice I have put a bottle of water in the freezer at the supermarket when we arrive, then an hour later when we leave it is quite cold if not totally frozen. Then put it straight into the coolbox in the boot. Never had any issues though sometimes we get funny looks from the checkout staff. Some people might view it as "incorrect" but I'm not sure it's breaking any laws.
If you go for many 5+ day trips, tbh I would look at an EHU and small fridge, you can then add a bit more comfort with a blow heater if needed.
I cannot camp without an EHU as i have to have electric at night for a medical device so i only use an electric coolbox, Mines is of them ALDI 12/240V ones, and its BRILLIANT!! Keeps my food and beer cold even on the hottest of day!
I have used it in a passive capacity too, and its worked great fore days out ETC when i haven't been able to plug it in :)
I have an Igloo Maxcold. I echo what everyone else says re the pre-chilling, making sure everything is cold or frozen. Also the water does keep it cold. I find cold blocks don't work that well, I prefer bags of ice and frozen bottles of water. Don't drain the water out! I made the mistake of doing that once and totally lost the chill. I use a plastic box and a tray inside the box to separate the food and keep some of it out of the water (e.g. salad). Take paper packaging off, use ziplock bags and clipboxes for anything that might leak. Make sure the things you need to keep really cold eg meat are at the bottom, salad/vegetables/cheese can be near the top.
On our last trip the local shops had sold out of ice so I froze some small bottles of water instead in the campsite freezer which worked fine, and there's less worry that someone will pinch it than with coolblocks.
I keep a cotton throw over the coolbox, as it's stored in the awning so sometimes gets the sun on it. That way it also doubles as a handy seat when I am cooking!
If you buy wine and beer, it can be chilled in a bucket of cold water first to avoid putting it in the coolbox warm.
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Topic: Keeping food cold!
