Seasea7

My partner and I are about to start the visa process from the UK. I am Australian and he is South African and we have our daughter who is almost one. I am under the impression that because we have been in a relationship and have our daughter he will most likely be granted PR straight away. My main question ( and excuse me if it’s stupid) what actual visa do we apply for? I’ve see subclass 801 and 301 and I and confused at what one to apply for ( leaning towards the 801) wanting to do this all with our a lawyer or representation so have lots of question thank you in advance z