Science student, but both my parents did Arts/Law, and a couple of friends are doing Arts/Law or law double degrees. Thought about doing a JD myself, but that would have to wait a few years...
Law is increasingly becoming less of a vocational degree (i.e. do law = become a lawyer.) Obviously, that's an option, but Law opens up a lot of other pathways. As you've indicated, the competition to get to be a solicitor is pretty intense, and the work hours/work life balance is also pretty intense (90 hour weeks are hardly uncommon.) Law degrees are a bit of work, but very flexible. It's not so much 'study law = become a lawyer = profit' any more.
Another major destination for (arts)/law grads is the public service (the federal and various state) public services. The usual way in here is through the grad programs. Pretty competitive, but a bit less then becoming a solicitor. Obviously, working for the APS (federal) will necessitate living in Canberra, but you could apply for the SA public service (I'm not sure if the NT has a grad program, or even a public service for that matter

). So yeah, government/public policy is where quite a few law grads end up.
Not really able to comment on journalism. But I wouldn't worry too much about actually doing a degree called journalism. With the right work experience/internships during undergrad you could set yourself up just as well as a journalism graduate. There's probably a journalism major within the arts degree as well, but be careful not to focus too much on it - don't want to put all your eggs in one basket.