If you are ill, you should inform the University of your absence as soon as is reasonably possible.  This can be done via the online Reporting Absence form which goes straight through to the School Administration Unit.  

If you have a minor ailment lasting less than seven days, you may self-certify, but absences of seven days or more require independent medical certification.  Saturdays, Sundays and public holidays count as sick days when calculating how long your illness has lasted.

If you will be absent for a longer period, you may need to suspend your studies for one or two semesters.  You can find more information on suspending your studies and the form for requesting this here.