A role as a Teacher Librarian can be extremely rewarding and dynamic. To be a Teacher Librarian, you will need an undergrad Education degree or a Grad Dip in Education and then Library and Information qualifications in Teacher Librarianship or vice versa i.e. Librarianship and Corporate Information Management and then a Grad Dip in Education. This is for School Libraries only. You do not need a teaching degree to work as an Academic Librarian.
For more information see the Australian School Library Association and the Australian Library and Information Association (ALIA) for some insight into what you might do in this occupation.
The Washington Library Media Association has published this short video on the valued role of the Teacher Librarian.