I got 23 in methods, did MTH1010 at Monash, barely passed.
Take it from someone who has been there and isn't being smug, danny isn't as wrong as some people might think.
Honestly, if for whatever reason you didn't do so well in methods in the first place, it is likely, in a probability sense, that you will have the same issue again. Whatever the issue is will vary: lack of foundation, lack of interest, poor study habits, lack of mathematical ability, etc. I had all these and predictably, guess what happened? I'm not being pessimistic but it is true.
It's an entire 2 years of VCE methods packed into a semester (12 weeks). It will be difficult, many people in my class failed. You can have no illusions about this matter, you must work hard. It is doable, im sure if you work your brains out, above and beyond, you can do it. However, it is above and beyond for a reason. I'm just trying to prepare you for it now, you can do it! But...you must not be complacent and you must remedy what caused you to do poorly in methods the first time around (or, in all likelihood, it will happen again).
Also, i'm not sure what UoM science is like but if math keeps coming up, you will have difficulty if you aren't great at math. I don't know how much math will feature in your chosen area but if it keeps popping up, you must consider how it will affect you. Alternatively, Monash science doesn't require mathematics as a prerequisite, that may be a good option for you.