There is no law around EV charging, but there are regulations around the type of cable used for EV charging. The cables must be made using H07RN-F cable or similar. There are cheaper cables that use standard 3-core "Hook-up" flex, which would break the terms of use of the chargers. Also, beware of short cables that use your EHU cables, as these would not be allowed.
I am an EV owner, and the slow 7Kw chargers that motorhomes would use are not favoured by EV owners as they would take around 15 hours to charge a car, whereas fast chargers can fully charge a car in around half an hour. Fast chargers are tethered, so they have their own cable installed. This is normally DC and could not be used to charge motorhomes.
The high street in my town has a row of 7Kw chargers in dual-use bays that can be used for parking or charging, which are becoming more common.
One of our members,
@Bruce Lauderdale, sells these cables, and there is lots of useful info on his website. He also has a discount code for out members that gives you £15 off when you spend £100 on his website. The code is: Motorhomer15
www.juicybrucie.com