We often do 'cheap' Holidays at such places as a second holiday with the 'family' (So 20+ of us at one time) just as a weeks' get together..
It's probably worth pointing out you are pretty much paying for the caravan and if savvy, even peak season you can have a family of 6 for £1100 (cheaper if you just want the caravan), plenty of other places than cornwall (Dorset/Lake District, etc)..
So yeah, £180-£233 pp for a big family peak season in the UK isn't the end of the world is it??
But going abroad, I also prefer privately renting a villa and flying over myself, the resort hotels are full of the same kinds of people I see in the UK Holiday parks, I only put up with it so the Mrs can spend the week with her family, but when I go for some sun, I want to actually enjoy myself..