You should discuss this with your supervisor and the RGS Office as soon as possible so they can provide you with the tailored guidance you require. If this is going to have a long term impact upon your studies, then this will not fall under Annual or Authorized Absence. Periods of mitigation which would only require a short period of leave would require you to follow the authorized absence procedure. Evidence supporting the reasons for this would need to be provided before or after the leave period, however your RGS Administrator will discuss this with you in greater detail. It would be advisable to log an enquiry from this FAQ.