From 1975 to 1984 Milne worked as a secondary school teacher, teaching English, History and Social Science at Parklands High School, Devonport High School and Don College. She first came to public attention for her role in opposing the building of the Wesley Vale pulp mill near Bass Strait in North Western Tasmania on the basis of its environmental impact. She also participated in the ultimately successful campaign opposing the Franklin Dam and was arrested and jailed in 1983. She worked as a research officer with the Australian Bicentennial Historical Records Search from 1987 to 1988.