I can see that the form when completed by the student/user/visitor is sent to the user/teacher email address identified in the form admin who can view it or go to the node to annotate it. Once annotated and saved, I would like to see a notification email sent back to the student advising them to check the teacher's comment/mark.

There is no need to show the results of the form in the email just a link saying "Your webform/assignment/whatever has been commented on please view it at ..."