Sites that don't have set pitches, such as Kingsdown in Kent, Dernewood, Bedgebury, Nethergong, , WoWo, Fallowfields, Blackberry Wood, and others - often found under the 'wild style' or 'back to basics' sort of listing.
But you will not get EHU, and there may well be restrictions like no amplified music etc.
Probably way too far, but I’ll mention one of my favourite sites anyway: Drumroamin (near Newton Stewart in SW Scotland) has immaculate grass pitches that are 10 x 10m. And you can pitch / park any way you want (“except on your roof”, said the owner) so it need not feel “regimented”. Small independent site, but I agree with recommendations to join CCC for their Certificated Sites. CAMC generally don’t allow tents, or only without vehicles, and their small sites often don’t have toilets.
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.