I am an Australian in Spain on a 8 month student visa. I'm wondering if I can apply for the 90 day tourist visa while I'm here. Another option may be to leave to a non-Schengen zone like UK and return to Spain to start the 90 day visa. Any tips would be greatly appreciated!
As an Australian citizen, you cannot get a short-stay Schengen visa under any circumstances. You can however stay in the Schengen area for 90 days without a visa, even if you have stayed in a Schengen country on a long-stay visa before.
See Does tourist visa (90 days) apply after a long-term visa ends in Schengen countries? and in particular this answer for the relevant law and this answer for an example of someone who did just that.