Breandán wrote:
Irish identity has Ó Gabhla for Goaley, Gooley, and Gully.
Tomás Ó Gabhla looks about right to me (but wait for more input.)
It's not actually possible to "translate" names. Nor can you use them officially without going through a deed poll, so this would be an Irish nickname of sorts.
If you are planning to use it on an Irish passport on the other hand, I believe you need to show proof you use that name in everyday life.
It is your right in ireland to use your name as Gaeilge Breandán to get a passport you will need to show photo id with your name on it easyist way to get this is to get a driver licence with your name but a word of warning if somebody is going to do this they need to go the whole hog and get everything translated as if you go abroad you are going to have problems explaining why your credit card is a different name than your passport/driver license.