Hi Gaye.
All depends how much your willing to pay really.
I will be in the South West then but I will not be staying in sites just car parks and pub stops. Moving on every other day or so.
If your feeling adventerous another option is Praa sands Cornwall in the car park owned by a guy called Norman, he welcomes motorhomes overnight 'stay as long as you want, as long as you buy a ticket' is what he says. £5 a night and some even had awnings up last time I was there.
We stayed 3 days and many were there for weeks at a time.
But as for campsites
Pentewan sands, and Porth beach tourist park both in cornwall are nice and without hills to the beach.
Watermouth cove holiday park in north Devon is nice too but more hilly.
Cherry tree farm campsite is next to the beach in Croyde bay too.