I have no problem with an early start Saturday. How about 8am? I've no problem starting earlier.
If we start in the town to shoot the castle then it will be easy for any late comers to find us. After that we can walk (5 minutes) along the Boyne to Newtown Abbey (nice old grave for Fluffy) & St. John's Priory. In the afternoon we can drive to Bective Abbey (10 minutes).
I'm working on plan B at the moment so if the weather is bad we can hit the studio. Don't forget to bring any still life objects you might like to photograph.