Weston was born at Caerphilly District Miners Hospital in Caerphilly. He was brought up by his mother, Pauline and adoptive father, "Lofty". His biological father served in the Royal Air Force alongside his mother. Simon lived in Singapore and at RAF Hospital Nocton Hall in Lincolnshire before returning to Nelson at the age of around six or seven. He has one elder sister, Helen, and three stepbrothers. At the age 14, Weston was given a police caution when he was caught as a passenger in a car stolen by his older friends.