I'd echo the comments about the Pembrey CC site. If you really want a pool you could try the commercial site at Cenarth Falls, which is a few miles from the Cardigan coast. It's been a few years since we last went but it had an indoor pool and was well kept, though to me was a little more cramped than the usual CC or C& CC sites.
http://www.cenarth-holipark.co.uk/