Im not sure if your labor laws are different in ireland than in the us. You could always babysit, get a paper route, wash cars, mow lawns, do chores, help an elderly person in the neighborhood with their chores or grocery shopping, you could make things and sell them on ebay, recycle cans, etc.
Babysitting maybe? ---Call around out there and see who would be willing to hire a 14 year old<3