Irony like to be restricted in my sleeping bag so I have a square end one. Dh and ds have mummy shaped ones. They are good vango ones that weren't cheap but worth every penny for the warmth.
Oh, I keep a "kitchen" box (plastic box with lid) in the attic for when we go camping. It has cutlery, plates, plastic glasses, salt, pepper, cork screw, mugs, dishes, sharp knife, kettle in. I just make sure it gets packed in the car each time and I know I haven't forgotten stuff.
I also pack into stackable plastic boxes with lids rather than suitcases/rucksacks because thu stack better in the car. They can then just be taken into the tent and stacked in there for easy access.
Oh - take slippers and big socks for inside the tent. Helps keep the muck and dust out. I stick one of the empty boxes in the porch bit to bung "outside" shoes and boots in (so everyone knows where they are even for late night toilet visits.
I assume someone has mentioned a washing up bowl. it can be a long walk to the sinks on some sites so you'll need something to carry the pots to and fro.
Fleece blankets are also great to wrap up in of an evening whilst sitting outside before bed.
If you do end up getting a connector for electricity, take a cheap electric kettle - boils twice as fast as one on the camping stove!