Speaking as probably now the second youngest here I’d say definitly go to the Higher Options event. While there I was still torn between a few colleges and courses and it really helped me to narrow down my choices. Once the people there think your interested they’ll give you all the time you want and go through the course specifics with you if your lucky to find someone involved with the course.
Oh and don’t forget to stop by the Irish Army stand and play with all the guns! :D
As for course choices, what the others have said is the best advice. I did Honours Maths, Physics and Applied Maths for my LC and its really stood to me so far in my course (BSc. Computer Applications in DCU) so if you do want to get into programming definitly consider those subjects.