Hello
My Great Grand Father was based there 1914 / 15 with 5th Battalion, Royal Irish Fusiliers,the 6th Battalion may have been there also. These 2 Bns were part of the 10th (Irish) Division,which in April 1915 went to Hampshire, then in July sailed to Gallipoli for the 7th Aug landings.
I tried to source a nominal roll of soldiers without result.
If your person was in the same units, I wish you luck.
The barracks still exist as Cathal Brugga Bks.
The answer to your question is to find out which Regiment / Battalion your man was in, then deal with the relevant Regimental museum (there may be a search fee involved)
Billy