We have an electric portable powerpack from Halfords for £90. So far we have camped up for 5 days without any facilities and have only needed to use it for OH razor and phone charging. It is 20 amp hours and will run the televsion for those crucial TV moments each day when it is wet. It also pumps up tyres - came in handy yesterday - and can be used as a jump starter
For hair I bought gas tongs, won't dry but will style and most sites have slot hair dryers nowadays.
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.