Hi!
I have studied both biology and chemistry VCE, and the answer to your question is that unfortunately, the content of VCE biology units 1&2 and chemistry units 1&2 are very different. I'm not really sure about tutoring, because there are tons of free resources that in case of your teacher not being competent, can help you since the stuff in chemistry are pretty universal and it's a waste of money if you just want to be well-prepared (Disclaimer: I am not implying that getting a tutor is bad/unnecessary or that you shouldn't attend headstart lectures. Just that keep the tutor money for when you actually need it and have a better idea of what sort of help you need.) VCE chem 1&2 does teach everything from the beginning, but familiarity is definitely a big help and advantage. Keep in mind that most VCE subjects are designed so that you don't need previous knowledge to study units 1&2. (Exceptions that I am aware of include maths and English mainstream.)
So yeah. Units 1&2 of bio and chem are unrelated.
But funnily enough, units 3&4 have some overlapping content! (It's not that much though, so don't get your hopes up.)
The overlap includes key science skills (all science subjects have this), enzymes, protein structures and biofuels are in both subjects. Their coverage depth can vary though in each subject.
TLDR: They will teach you what you need to know in chemistry. Biology and chemistry units 1&2 don't overlap, and units 3&4 do so minimally. Don't rush to get a tutor before actually finding your weak points because there are free resources and help available!