Well, time to update this!
First of all, thank you so much to everyone who wished me luck & offered advice, means a lot to me.
So, how did things go?
Both my parents came along with me to the interview, and provided amazing moral support. The teachers, particularly my English teacher, tried to lull me into owning up to cheating a few times, but I adamantly told them that I made an honest mistake with no intention to cheat or break any VCAA guidelines. After a while, they relented and told me that given the issue at hand, they'd offer me three options. I resit the SAC, but have to provide yet another 90% copy of my essay, which I decided would be far to strenuous. The second option was to be graded on my original failed attempt in the first period, about 3 pages of a poorly structured essay not remotely finished. The final option, the option I chose, was to sit a test on this Friday after, written or oral, based on the SAC I've written. They'll be questions about the overall structure and the themes I discussed, and considering it is my own work, I should be able to pass with flying colours.
So, everything has really worked out to the very best! My English teacher is being reprimanded for poor conduct throughout the SAC (failing to monitor the room, and to notice my mistake) and I am on my way to receiving close to full marks for my essay, based on what a coordinator told me.
Thank you very much to everyone who offered advice and showed support, means a lot to me guys!