Hey Lanky - that's my back yard. Better bring yerr passport!
Get down to Ferryside (a couple of miles away) around 1.5 hours before HW and take a very pretty run up to Carmarthen on the Towy. You can take the SIB up the slipway on the town quay and have a shant/lunch in one of the many hostelries within a couple of hundred yards. The Quayside Brasserie is, well, I'll let you work it out yourself......
Alternatively, get down to Kidwelly and play around Carmarthen Bay, if it's not too rough, or down to Burry Port and run along the coast to Llanelli, alongside the Millenium Coast Path. You could take the SIB ashore on Llanelli beach and have a bite to eat at the visitor centre on the seafront. If it's calm enough, you could cross the estuary from Burry Port to the North shore of the Gower peninsular, but beware, that's the habitat of The Jack, so you wouldn't want to leave your SIB anywhere for any period of time, or you'll be swimming back.
As you're within an hour of Pembs, it would be silly not to venture down to the Cleddau and have a run up to Cresswell Quay from Lawrenny or Neyland. Endless opportunities on that river.
Giz a shout nearer the time and we can have a chat in more detail.
Oh and although in the South of the Principality the area's known as West Wales. South Wales is further over to the right.