Career
He played his club rugby with Young
Cotter joined the senior squad at the beginning of the 2012-2013 season, having earnt a development contract after two years in the Academy. Cotter made his senior debut as a replacement against Connacht in the Pro 12 on 27 December 2013. He signed a one-year development contract extension in March 2014.
Cotter joined London Irish on a short-term loan in September 2012, replacing his teammate John Ryan.
Cotter joined another Aviva Premiership side, Bath, on loan in November 2012. In July 2015, Cotter moved to Aix-en-Provence in the south of France to play with the Pro D2 side.