Just to confirm that I have access for the group to the maritime museum on September 25.

This is the building, As there are only two tall spires in Dún Laoghaire, you are sure too find it 

On Google Maps: see here  (It was a church, so look for the cruciform shape)

The Kingston "Minotel" is to the right, on that map - hope to see you all - ClemMcGann