IT is an extremely competitive field.
My personal thoughts are that you would be getting a uni degree for the look, rather than anything. Again, really competitive.
I have an IT degree myself and realistically if we lived in an ideal world, practical TAFE/hands on learning would be sufficient.. unfortunately most employers in the IT field look for a Bachelor degree minimum.
If you intend on creating your own business in IT, then practical training would be sufficient. But for anything decent, uni is the way to go. This is coming from somebody who knows quite a number of people in industry now via my uni days (in various areas such as programmer, database admin, developers etc).
In regards to uni itself, I know somebody who entered uni that left school during Yr 10 and did a diploma first at a RTO. If you were to go down the non-ATAR path, you'd need something else to back yourself up with (such as a diploma or cert recognised by the uni you want to go to).
My advice would be to look up some job ads in an area which you'd potentially be interested in (e.g. database admin, front-end developer etc) and see what the job ads are requiring. That will give you an idea.