Wow, thats a lot! The most I paid for a 6' x 4' bit of grass on the C2C was £10. OK three years ago but I thought I won't go to that site again! The most I've paif for a night is £15 in Kent. I will not be going there again either! I have now organised myself to be completely self sufficient for sleeping and hygeine, I even have a shower in my rucksack, so am getting into wild camping more and more. I don't mind going on a site (for a treat) but I would prefer to spend my money on food and drink in pubs.
I learned my lesson when I hiked the GR10 in France in 2015, because I stayed on so many sites and spent so much elsewhere I didn't have any change out of £1200 by the time I returned to the UK. I have found its quite easy to spend about £40 a day, travel costs, site costs, daytime food, evening food and drink and general entertainment, so I felt I had to have a proper rethink of the way I did my hiking.