Buchanan was born in
Christchurch on 28 September 1945, the second of six daughters in a musical family, and was educated at
St Mary's College. She graduated with a Bachelor of Music degree from the
University of Canterbury in 1967 and a teaching degree from
Christchurch Teachers' College in 1975. She married physician and endocrinologist David Carroll, and the couple went on to have one child. Buchanan has been active in music education. In 1976 she became New Zealand's first composer-in-schools, remaining in that role until 1993, and has been a guest lecturer, adjudicator, musical director, advisor to teacher support services and an assessor with
Creative New Zealand panels. In 1979 she served as president of the Composers’ Association of New Zealand and founded the Christchurch Music Workshops. In 1980 she co-founded the music publishing cooperative Nota Bene, which provides a hire library of music for schools and community use. Buchanan was the composer in residence at the
New Zealand Film Archive from 1984 to 1993. ==Honours and awards==