Found the solution to my problem - How to lock classroom pane/options with a custom profile in JAMF explained in first comment
We are looking into deploying Classroom for our teachers and students next year. We would be doing Teacher Managed classes. (macOS devices, teacher and student). By default, students can change settings that include them being able to leave the class, and requires student approval to lock etc... Which is never going to work.
JAMF has a couple wonderful configuration profile setting under Restrictions - Functionality. However they ONLY work with Prestage Enrolled devices, not those enrolled via QuickAdd. I have tested and confirmed that with a clean install of 10.14.4 and QuickAdd that the configuration indeed does nothing. Students can still change settings and require permissions etc.
Allow Classroom to perform AirPlay and View Screen without prompting, Allow Classroom to lock the device without prompting,Require teacher permission to leave Classroom unmanaged classes
Solution Below - I honestly don't know why Apple (and to an extent JAMF) have locked this behind a Prestage requirement, pushing their own agenda I suppose.