There is also the Fishguard to Rosslare ferry option.
The ferry actually goes from Goodwick though, which is about a couple of miles down a steep twisting hill from Fishguard itself, but is a less 'lively' place than Pembroke Dock.
That said, the residential area in Goodwick is fairly small. Bit of a risk regards finding a potential parking slot in good time I'd say.
Sorry, this isn't much help.

Good luck with it Spedger, and your trip.