I didn't do methods in year 12 and so took a bridging course through open universities. It matched the requirements fine, I just had to get a letter from VTAC stating that it was equivalent to methods (I'm in Victoria, so you might have slightly different requirements).
I found it gave a really good basis, especially for calculus, here's the link if you want to check it out:
Fundamentals of Mathematics. Takes 3 months to complete