The larger ones are heated. (Haven't seen inside the smaller ones). They also have electric points so you could bring an extra heater, TV (reception is crap tho'), playstation, whatever.
They're warmer than a tent, definitely. Oh, and you're allowed a campfire which makes cold, still nights an absolute delight for the wee ones.
Trouble no one about their religion;
respect others in their view and demand that they respect yours.
~Chief Tecumseh~