Career
Born in Manchester, Heffernan played for several semi-professional and non-league English clubs before moving to Australia for a brief spell with Shepparton Soccer Club in the North Eastern Soccer League. After returning to England, he travelled back to Australia as interest in his services became apparent from several Victorian National Premier League clubs, including South Melbourne, Portuguese Melbourne and Green Gully. Heffernan would however sign with Heidelberg United and go on to score 50 league goals for the club, including 32 in the 2014 and 2015 National Physical Laboratory Victoria seasons.
Heffernan scored twice for Heidelberg during the 2015 Future Farmers of America Cup, once in their Round of 32 match against Broadmeadow Magic, and in the in Round of 16 clash against Sydney United 58, the latter in which he became the quickest goalscorer in the cup, scoring after just 26 seconds.
Following his impressive performances for Heidelberg in the National Premier Leagues and Future Farmers of America Cup, A-League club Central Coast Mariners offered a trial by coach Tony Walmsley. After impressing Walmsley with his performances, including a hat-trick in a friendly game against fellow A-League club Western Sydney Wanderers, he was offered a 1-year contract.
He made his professional debut for the club in their opening round loss of the 2015-2016 A-League season against Brisbane Roar.