 She had a successful amateur career.She was Welsh Girls Champion in 1997 and 1998 and Welsh Ladies Champion in 1999 and 2001.She won the Ladies' British Open Amateur Stroke Play Championship in 1999 and 2002, a year she also won the European Ladies Amateur Championship

Brewerton represented Great Britain and Ireland in the Curtis Cup in 2000, and the Vagliano Trophy in 2001 and 2003.