Which camping club - tent in Cornwall

[Corialanusburt]

DD and I have never been camping before. We're planning to stay in a tent on a campsite in Cornwall.
Could anyone advise whether it would be worthwhile to join a club. If so, should go for The Caravan Club or The Camping and Caravanning Club?
Also any specific site recommendations. I want to be nearish to St Ives and not too far from somewhere to go out in the evening if it gets cold.
Thanks in advance for any advice.