That's great to hear you're considering to study medicine! I will say that I should correct you in your statement about the pathways to medicine. There are two pathways: provisional/school leaver pathway and the graduate pathway. Each university will have different requirements for each pathway and upon completion of their program, you will receive either an MD or a MBBS (as you know, most are MD now). For the MD, you will end up with 2 degrees including the MD. May I add that, technically speaking, there is no difference between MBBS and MD in employability. As far as I also know, JCU is the only one that provides a MBBS which is 6 years but FYI, Monash university is only 5 years which goes to show that an MD can be shorter than an MBBS.
As I was saying above, there are different requirements for each uni. As you didn't do UCAT, there are a few unis that can still take you through the provisional/school leaver pathway and that depends on either your ATAR only or ATAR + interview. For example, Griffith university takes only ATAR (99.85), University of Sydney takes your ATAR (99.95) and interview, JCU takes a little of your ATAR but mostly, a written application then an interview.
Another way is the graduate pathway which there are also different requirements. You can either take the UCAT next year and apply for certain unis that will take you like UNSW (with an interview), however, you'll have to be careful because unis like UQ don't take people who do UCAT after grade 12. Or you can do GAMSAT; with successful completion, quite a lot of unis will take you but likely, with an interview.
As you can tell, there is a lot of research you need to do and the above info came off the top of my head so please go verify this and see for yourself which unis require what and determine which one is best for you. I went through the school leaver pathway; its just that after you get in through Grade 12, you don't have to worry about anything like GAMSAT/UCAT except for your GPA. Nevertheless, good luck and hope this provided some info into medicine pathways!