If you need approval for additional units while you're on exchange contact your Student Advising Office.

You will need to provide either a link to the handbook/course catalogue description of the unit or a unit outline in order for the school to make an assessment. Details such as credit points (or similar) associated with the unit, class contact hours, mode of assessment and unit content will also be important. 

Note: unit approvals can take time to process, make sure you forward your information well before any host university enrolment deadlines.