Camelia Garrett’s taking on the 26.6 mile challenge as a thank you for saving her twins lives back in 2003, born 11 weeks premature.
Twins Etti and Owain are turning 18 later this year, some of the staff who cared for them still work in the department.
Camelia has undertaken a gruelling training regime to get ready for the big day and aims to complete the event in five and a half hours.