"Is business right for me?" is a question that only you can answer. Don't choose a subject just because you have to or have no other options. You should choose subjects based on interest and prerequisites for uni courses (they are the two main reasons why you should have x or y subject in your list).
Anyway - you definitely can do Business 3+4 without 1+2 knowledge. Business is very theoretical but can be easily learned

Also keeping in mind Business scales down in general, if that affects your decision making in any way.
This is why you're at school - to learn. While alot of us tend to get caught up in the hype of competition and ATARs, the primary objective of schooling is to learn and grow. Just because you don't know anything about business related stuff doesn't mean you can't learn it as you go.
