Newport Tredegar house cc site. ( sadly I live in newport and it is very poor and run down ) the site is. However very nice in the grounds of a NT property well worth a visit . As is cardiff . And the folk museum at st Fagons .chepstow castle and the wye valley are not too far .
Or look near Brecon . Brecon cc site or pencelli . Also. The cc site called Pandy is lovely .
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Good luck .
Blossom Touring Park, Abergavenny or Rowelstone in the middle of knowhere (but lovely). A great area to choose, also visit Blaenafon Ironworks (which is good, and free). Oh, and Castell Coch, just north of Cardiff.