Turner was born in Northampton, England on 21 February 1996, the daughter of Sally, a nursery school teacher, and Andrew, who works for a pallet distribution company. She moved to Chesterton, Warwickshire when she was two years old. She attended the independent Warwick Prep School until she was eleven, and later attended the independent and fee-paying The King's High School for Girls. Turner has been a member of the theatre company Playbox Theatre Company since she was three years old. She has two older brothers. Her twin died before birth.