Good day,
I have managed to sort myself out, the documentation at the bottom of the page on (https://gluu.org/docs/gluu-server/4.3/user-management/scim2/) showed me what to do, I was using the wrong scope when I tried to retrieve my token, as the "write" user scope was accidentally re-named on our instance ("https://gluu.org/scim/users.write"). I have corrected it and now can interact with the API as I should. Thank you.