if you have a warehouse clearance store near you ............. they have a small (about a foot high or less) electric infrared heater, for £5.99 , i dont have ehu but it looks ideal for those that do and require small heater. think it might even have thermostat. happy shopping.
Just a point to consider...it seems that some campsites are now asking anyone using a caravan awning to have a gas heater rather than electric!! Now I don't know if this is going to be extended to the tent fraternity, but it's all in aid of 'greener camping' and if that means the site can still charge for electric and you not be able to use it, then you can bet your bottom dollar that it will happen.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.