Hi James,
You can edit the standard automatic notifications. In the course, as an admin, click on the title of the F2F activity. The Administration block will now have a "Facetoface administration" section, which contains a "Notifications" link.
The approval request and cancellation messages are among the messages contained here, and if you edit them you should see the checkbox to "Send a copy of this notification to the user's manager". Simply turn that off and the manager copy notifications should stop going out.