Barmaid....St Davids isn't that far from Fishguard. You can get a boat from near the Lifeboat station :::::
http://www.ramseyisland.co.uk/
The boat trips are a bit scary for me, but the boy should be in his element !
I have dim of an Aquarium at Fishguard, over near the Irish Ferry port.
He might like Strumble Head lighthouse, which used to be open to the public, although may not be now...spectacular coastal scenery, with a good chance of seeing seals at this time of year :::
http://www.visitpembrokeshire.com/explore-pembrokeshire/towns-and-villages/strumble-head/
For you, there is a real old-fashioned Pub, in the Gwaun Valley, just south of Fishguard...."Bessies", as it is known...she still serves beer from a jug !
And there are not one but two Breweries in the Valley !
http://www.newportpembs.co.uk/articles/gwaun-valley-newport-pembs.php