Tŷ’r Sgwlyn is between Fishguard and St. David’s, in the village of St.Nicholas/Tremarchog.
Journey time by car from Cardiff Gate services on the M4 is about 2 hours.
Best route advice by far is to go via the M4 and A40: aim for Carmarthen, Haverfordwest and Fishguard. Do not even think of country routes unless you have plenty of time!