Though her family moved to New Zealand when she was nine, Cokayne made the choice to train for England after being called up to the New Zealand Women's Rugby Team (known as the Black Ferns) training camp; she moved back to England in 2013.[5]
The following year she was selected for the England Under 20s team, and made her first appearance for the seniors England Women's Rugby Team in 2015. She scored her first senior try for the side against Canada in the 2015 Super Series.[6]
In 2019 she was awarded a full time contract with the England team. She missed some games that year, including the 2019 Super Series, as she completed her RAF training.[6] She was named in the England squad for the delayed 2021 Rugby World Cup held in New Zealand in October and November 2022.[7]
Born in Ipswich, Cokayne first played rugby at age six, at Cleve Rugby Club in Bristol. She also played football as goal keeper for Aston Villa Under 10s. Cokayne's father was a big Aston Villa fan: her initials spell out AVFC.[5]
She was nine when her family migrated to New Zealand in 2006 because her father joined the Royal New Zealand Air Force. She attended Feilding High School and captained the girls rugby team in 2012, winning 53 consecutive matches.[6]