In order to be able to charge for parking, the operator of the site must clearly display signs stating what the charges are. If such signs are in place, anyone who then uses the car park enters into a contract to pay the charges that he/she has been notified of. It's entirely up to operator of the car park as to how such charges are enforced. (i.e. it makes no difference as to whether cameras are used or whether a man with a notebook patrols the car park).
Businesses using CCTV must register with the Information Commissioner’s Office and notify people who might appear in the recordings that CCTV is in operation:
https://ico.org.uk/media/for-organisations/documents/1542/cctv-code-of-practice.pdf
However it's extremely unlikely that a court would rule that failure to do so could invalidate any parking charges, as the contract between a car driver and the operator of the car park is independent of the rules relating to CCTV.