My previous experiences with “volunteer insurance” in other fields has been that you can only claim for costs you might not be able to recover elsewhere.
So, possibly, you would be lucky to get anything for
Medical expenses- covered by Medicare or private insurance.
Time off work- covered by your employer’s leave allowances
Not working? – covered by Centrelink payments.
Perhaps you could do better out of the Public Liability cover if you could prove OC negligence.