We are members of the c&cc with a 10 yr old son who is quite shy at meeting new friends on a site, we have started to use THs and rallies as there are generally other kids on site who seem friendly. If your prepared to try non elec it is def worth a try, lot cheaper to.
Another vote for Temporary Holiday Sites (listed on the Camping & Caravanning Club website, with fuller details available to signed-in members).
Many are held during school holidays, some on own sanitation essential sites (water and toilet disposal point will be available) or you might prefer choosing one held on the "rally field" of a commercial site allowing the use of their facilities, occasionally even with EHU on offer.
Prebooking is rarely needed (except for EHU where available) and you can usually stay for one or two nights or for the duration of the THS.
And as Anne-Marie says, inexpensive, even if you take the annual C&CC membership fee into account.