I didn’t do the leaving cert (I’m from Glasgow), but in school I picked maths, music, Spanish, physics, chemistry and English. I imagine you’ll have similar options.
All of them have helped my career! I think it’s good to pick a range of subjects (if you can) because you learn so many skills which is most important. For example, music teaches you to be creative which you still need in science. English helps you understand appropriate writing techniques for writing lab reports, and then of course the sciences are relevant because I have built on the core concepts from them in my job!
Sometimes you have to pick certain subjects for a particular university course – so make sure to check that out when the time comes for picking subjects.