What is the course in question? If it's over 500 points, then you will need 4 a-levels regardless of which university it is. UCD is a great university, it excels in science, business and arts in particular.
You are applying to the CAO, not the individual universities. CAO manage everything- the universities in question will not know you exist UNTIL you accept your offer. That's the case right now, thousands of students who accepted their offer yesterday are only now going to get stuff sent out to them.
If you don't have the points or the entry requirements for your first choice, they move onto your second. If you don't have the points or requirements for that, they move onto your third and so on. Say you get an offer for your third choice. That means that even if you don't accept it, you will not ever be offered anything lower than that as those choices are automatically scrapped. You CAN be offered your first and second choice in a later round, if the points go down or if your remarks boost you up etc. Individual universities on your list haven't a clue you exist (until offer accepted as I said) and don't know what else you picked.
I heard Wales do funding for students studying abroad, but England and Scotland don't. If you think about it, why would they really? Ireland does not do loans, especially now after the crisis, there never was a student loan culture in the first place due to the no tuition fees. You can't get the grant until you are here for 3 years. You CAN get a job with most courses though, and they pay very highly, minimum wage is much much higher here. Fees without tuition fees are €2500 a year.
Also, what is the student life like? Is there lots to do, clubs etc? Or is it more quiet?