Thank you for your question. I understand that your uncle who died has left your father as the last surviving sibling, and there are no parents, or children, or surviving spouse / partner alive. The legal situation in this case, if there would be no will, is that your father is entitled to the entire estate of your uncle.
It is the duty of the persons interested (i.e. the persons appointed through a will) to present a will. As long as you do not have a will, your father may apply for a grant of letters of administration, just like your uncle would have died without a will (information on how to apply is here: http://www.courts.ie/courts.ie/library3.nsf/pagecurrent/7176C696FD04A8CE802575AF003E0ECF?opendocument&l=en). To be very fair, you could inform the Probate Officer that there is a person having a power of attorney from your uncle, so that they can make the respective official inquiry on whether this person has a will in their possession. You could also inform the person beforehand that you will be applying for letters of administration as if there would be no will. They will be certain to reply, because they have to conserve any rights granted to them in the will.
If they have already received Probate, then of course the will becomes public and can be requested by you according to the instructions available here: http://www.courts.ie/courts.ie/library3.nsf/pagecurrent/F2051BFE4462AAB3802575AF003E0ED0?opendocument&l=en.
I hope my answer was useful and look forward to your rating, which is essential to my activity.
Dr I L Vlad