Even though Nicola landed her first acting gig in 1997 (an uncredited role in the action thriller My Brother's War), she spent many years struggling financially before finally securing the role of Clare Devlin in Derry Girls. "My 20s were crazy tough," she told Elle during a December 2020 interview. "I was broke all of the time. If I wanted to buy a coffee, I'd be terrified my card would get rejected. It was all that stress."
However, Nicola continued to pursue acting. She trained at both the Oxford School of Drama and Birmingham School of Acting, and she graduated from the National University of Ireland, Galway with degrees in English and Classical Civilisation, all while appearing in theatre productions. "Because I come from a background in theatre and doing little fringe plays, and wondering if 20 people would come to see it, I think that hunger and fear don't leave you," she told Elle. "I'll always have that motivation and drive to be like, 'Please come and see my play.'"