The first time we went camping we went to Tenby which is a 5 hour drive from home. Don't be shy, just go where you want... most things you can pick up where ever you are so no biggy either way.
Don't know too many sites around either of the areas you've said. But check out the campsite review, they are generally very accurate.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.