There are many ways to travel once you are in Ireland. Joining a club can be an excellent way to meet both international and Irish students, and provide excursions you might not do on your own.
Students also enjoy renting bicylces and hiking.
It is a good idea to add extra days to your overseas stay for travel, especially after your program when you will have a better idea of what you don't want to miss. Check with friends, the Students Union and travel agencies for tips and discounts. Former participants recommend the International Student Identification Card for discounts on transportation.