Gaffney was part of the 2021 Women's Six Nations Championship team and played in the team's defeat to England and Italy ahead of their closing game against Wales, which they went on to win. Ahead of the match with Wales she told the BBC, "A win would be amazing. There's that saying, 'sometimes you win and sometimes you learn'. I feel like I've learned everything I need to know, I would like to win now." During the match she scored the team's first try. She was also part of the 2020 Women's Six Nations Championship, which was disrupted by COVID-19.