McColgan was selected for the 2008 Commonwealth Youth Games in India but suffered a major knee injury which it took her a year-and-a-half to recover from. She also missed the 2011 World Championships, held in Daegu, South Korea, after breaking her foot at a Diamond League event in London. Her senior debut for Great Britain came at the 2011 European Team Championships in Stockholm, Sweden. Initially selected as a travelling reserve to cover a range of events, she was called upon to compete in the 3000 metres steeplechase, an event which she had only competed in twice before, and ran a personal best while finishing ninth. She came fourth in the 1500 metres at the 2011 UK Indoor Championships and won the silver medal in the 5000 metres at the UK Outdoor Championships. She won the gold medal in the 1500 metres at the 2011 Scottish University Championships.