Blue ikea bags, I each, for everyone's clothes etc.
Plastic/foil backed picnic rug for sleeping area to reduce heat loss into the cold ground.
Wooly hats for sleeping in (seriously!) to keep heat loss at a minimum.
Put on an extra layer after dinner, BEFORE it gets cool. I tend to put on a thermal layer under my "daytime clothes" to sit around relaxing, and then when I change and put pjs over the thermals later on, I am not letting cold air get onto my skin just when I want to be cosy for sleep.
Carpet for living space is really a great idea - but until you know if you want to camp, get a mat like you'd use at your front door (a rug one, not a scratchy coir one) or an empty cardboard box you bring your food in flattened out - to make a mat at the entrance to the tent. All boots etc get changed as you walk in, and crocs/flip flops for indoor use.
Bring cards to play with if it rains and you are confined to the tent. (Try and find somewhere that has a tv or games room, and/or local entertainment options like cinema or even nice coffee shop for juice and a bun, in case of bad weather).
Fill a kettle with hot water when you go to bed - either an immediate brew or faster to heat the water for the brew in the morning makes a big difference! If you are cooking on open fire, always use spare time when not cooking to boil kettle for washup water/flask/hot water bottle in bed etc purposes. And boil water for cooking rice/pasta/potatoes etc in the kettle first as it really does heat up faster and saves your gas.
Lots of camping kit doesn't need to be specialized camping kit. I have an Ikea plastic tub that holds my "kitchen" (for camping and self-catering cottages combined - I need firelighters more when camping and dishwasher tablets more when renting a cottage!). It has some proper camping gear, but regular wooden spoon, set of Ikea plastic cooking cutlery (very cheap but handy for non-stick camping pots - spatula, whisk, slotted spoon, tongs), tin opener, corkscrew, silicon oven-mitts, Ikea kids plastic plates (big lip so great for sloppy dinners for all) and glasses etc. And then camping sporks, pots, pan, kettle, "Granpa's fire fork" etc.
Head torch each, and a few hand held torches, as well as a lantern for the tent. And spare batteries. (At night, I turn 1 headtorch to shine through our 10l water barrel to make a low but sufficiently bright lantern as a camping hack I'd seen somewhere).