I've had my head buried in the sand too but as ive, for the first time ever, got my work done in 5 weeks instead of 6 and have some free time, boredom gave me the sudden urge to get my finger out and start insulating the van. Got some 25mm (not very thick I know but better than nothing, please allow me to deceive myself!!) polystyrene sheets from b&q and set about putting it on the roof, doors, sides etc. I'm going to keep the chill off through 3 strategically placed 60w greenhouse heaters. I'm also told that putting a 30w aquarium heater in the tank overnight gives off just enough heat to stop the water freezing. I'm doomed to failure I know but as a thrifty (keeping it polite!) Yorkshireman I just can't bring myself to use a 2kw heater.