If you want to specialise in server engineer or the such I personally wouldnt bother with the TAFE stuff. Get in on the ground floor with a major corporate CSC for example (I know many dont like CSC, but its easy once within to move forward to better positions).

Like you I have a business degree and no formal qualifications in IT, I did some of my Microsoft exams and then just applied for every server job from there. Didnt take long to get a low paying server engineer job with AlphaWest. After a few months the world was my oyster and quickly progressed with other companies to a senior engineer, technical lead and team lead.

Employers look more for experience than qualifications in my opinion, but when starting to tell you the truth its more personality and bullshit. You will have to start at the troubleshooting helpdesk server problems and a few years of that possibly before you can proceed into something specific.

By the sounds of it you have the basics there, I think its time to jump ship and just apply for server engineer jobs. Once the recruiters know you something will pop up sooner rather than later.