Susan was born and raised in Rukuhia. She boarded at Waikato Diocesan School in Hamilton and King's College in Auckland, and later graduated from the University of Otago with a Bachelor of Laws and Bachelor of Arts.
 
She is married to John Hayward and together they have 5 children. Their farm, Judge Valley Dairies, has won multiple awards at the Waikato Farm Environment Awards.
 
From 2016 Susan was elected to the Kakepuku ward of the Waipā District Council. She was re-elected unopposed in 2019 and chaired the Council’s Strategic Planning and Policy Committee. In October 2022 she became the first female Mayor of the Waipā district