Hi Linda, it is fantastic to hear you're planning an Irish road trip!
To get to your rental purely by public transport, the best route is to catch the
Dublin Bus (Route 53) directly from Ferry Terminal 1 into the city centre (getting off near Busáras/Central Bus Station). From there, you can hop on the
Dublin Express coach, which will take you straight to the airport.
Also, I recommend downloading the
TFI Live App for real-time bus tracking, and you can read more about island-wide travel on the
public transport hub on the official website of Ireland.com.
Hope this helps clear things up, and wishing you an absolutely brilliant road trip! 💚