Andy,
great to hear that you are using
https://www.map.armyI assume your instructors have a separate GIS application to generate the OS maps which could be added as map overlay in www.map.army. The instructions on how to generate such an OS map export can be found here:
https://osdatahub.os.uk/docs/wmts/gettingStarted From a technical aspect it would be possible to integrate the support of OS Maps into www.map.army using WMTS. This would eliminate the requirement to export and import OS Maps … Would you benefit from such improvement?
Best regards
Martin from the map.army team