Next week I will move onto a farm for a few weeks. I'll be sleeping in a family sized tent. I want to be comfy and my Sea to Summit Ultralight mat is fine for a weekend (5cm deep) but I'd like something at least 7.5cm deep and wider than 55cm ideally.
Go to Millets and buy a cheap airbed and pump for around a tenner? Massive thickness to soak up any uneven ground, it's what we use for family camping and been good for us.
I guess it comes down to cost and future use intentions. If it’s something you will want to use again for car camping then the thicker Exped or Robens mats are probably the answer(more expensive).
Cheap air bed. Cost about £20 and are about 12 inch thick. Very comfortable and if you put a duvet underneath you as well as one on top it massively increases the warmth.