Sorry if I'm repeating...
We've found this campsite website www.ukcampsite.co.uk useful for reviews. Definitely stay somewhere with good reviews for the toilets/showers 
Get a good quality cool box and you can also fill it with ice to keep it cool (and you can use the ice with drinks). Sites that will freeze freezer packs is also good. I make chilli and freeze it, its then easy to reheat (mix with a microwave packet of rice) to make a really quick meal, plus keeps milk cool on the way there. We also bought a small travel BBQ and then cooked evening meals on that. Don't be afraid to eat out, have pastries for breakfast etc, all things that make the week easier, it is a holiday after all.
A camping kitchen is good for keeping food away from critters and ours has a little top to it where you can chop/prep food. Take a washing up bowl and ideally a folding drainer to stack it when using the washing up station.
Flip flops or crocs are essential wear for getting to/from the bathroom and also to wear in the shower. Take a plastic bag (like a beach bag) to hang on the back of the shower door to keep your clean clothes/towel/shampoo in etc. There might only be one hook to put everything on and you don't want your PJs to end up wet on the floor.
Find out where to buy fuel for your stove from. Can you get it anywhere or just one shop? Make sure you take enough or know where to get it from. We use a methylated spirit stove as you can buy meths from any hardware store.
Take pegs, you can then peg your tea towel on the guy ropes to dry, especially if it's windy.
You don't really need carpet but definitely take a cheap rug (i.e. a rag rug) for each door way. It will stop wet tracks/dirt getting on the groundsheet and if it is a bit wet/windy, any rain won't get far under the door.
Evenings can get cold, even in the summer. Plenty of layers and a nice warm jumper. We ended up buying windproof jackets on our first camping trip!
Have a brilliant time 