Depends how mathematically inclined you are. In Further, the majority of the course is stats, you would have done some in year 10, so bear this in mind when you consider Further. As for the feasibility to pick it up without 1+2, it is quite doable, general maths can be covered a (committed) week by an average student of mathematics. For 40 raw you will need A+s which you probably already know corresponds to the top ~10% of students (whilst 40 raw is only 8%). For this you need ~ 93% in th MC exam and ~87% in the long-answer exam, I believe.
As vexx said, the majority of the material is quite... basic... so practice is quite essential. Unless you naturally make no mistakes whatsoever. Stupid mistakes are what destroy most (decent)Further students.
Also, not
that many Spesh students do it(because only 2 maths can be in the top 4).
and yeah, further maths is like boringest shit ever... unlike REAL maths (methods & spesh)
They aren't 'real' maths either. Getting there though. All VCE maths is poisoned by the fact that
everything is centred about assessment. Not to discount the material itself in any way.