Good afternoon,
If your g uncle decided to enlist of his own accord then he would probably have gone to the regt'l depot of his choice and signed on the dotted line, Dubliners or Leinsters most likely. However, if he was picked up by the recruiting party in the area at the time then as Neil says, it could have been almost any regt in the british army although the most likely would be infantry or cavalry as they were usually in the majority. If you post his name and any other details you have on him then we have the people to find him for you or give you the leads to follow up yourself.
John915