if it’s emergency, apply for bridging visa b for your partner.
Some times they will grant it in 48hours.
You can write a letter regarding the current situation and urgency to be in Uk. They will give you at least 3 months min. BV B(unlimited travel).
Meanwhile use the visa and once he’s there he can create documents and submit it to the immigration.*** But make sure he’s back in aus before bridging visa b expires**
I have also seen some post where people have lived in different country due to parent health issues and were requested to come back when their application was decision ready. One person got BvB for 1 years
My BVB grant was for 6 months(reason for travel: meeting friends and family) I had even mentioned 2 months stay period but they gave it for 6 months.
Meanwhile you will have to inform immigration about his new address(if applicant is staying in different address for more then 14 days).
All cases are different so make sure you ask some experienced agent.