Help needed in regards to Migrating to bristol (Bristol)

Hi Everybody,
I was wondering if anyone can help with information in regards to Migrating to Bristol from Australia. I may need to look into a Spouse/Permanent Visa. My Girlfriend's little sister has been involved in a accident and is in critical condition in hospital and we may look into living here for her long term, I have been travelling for 10 months and not looking to going back to Australia anytime soon, but what I've read I may need to head back to Australia to obtain a visa does anyone know if that's the deal in regards to a Spouse/Permanent visa?

any help or information and be much appreciated.

Kind Regards, Phong