He is hoping to use his Ireland experience to Wigan boss Roberto Martinez's advantage, just as he had to adapt to his move from Scotland originally.
McCarthy said: "At first it was tough. I didn't play for six months and had to work hard. It's a tough league and the pace of it, with respect to the SPL, is a bit quicker.
"It's a hard league to play in so I had to wait for my chance and then when I got it I stayed in the team, which was a great achievement. Leaving home wasn't easy either, but everything is going to plan now.
"My family, my mother and father, my brothers and sister and uncles have been there for me all the times, and the older pros at Hamilton and Wigan, and the gaffers and all the staff have done well for me.
"I am still learning. I am young and have a lot more to learn. I've got to keep working hard in training and the experienced boys will keep me on my toes."