IB curriculum and subject choices

So I recently moved to an IB school from an IGCSE (International GCSE) background. I’m the only student that hasn’t come from the usual MYP background which leads to the IB diploma program. I have been told to take 4HL’s and 2 SL’s. I went with it and my classes are starting tomorrow but i’m still unsure about being able to handle it. So far I have chosen
HL- maths, english lang/lit, chemistry and business management
SL- chinese, environmental sciences
Honestly, I just want to know what it takes to get a 40 and above score in IB, and whether or not the path I have taken to achieve it is a realistic one. Please let me know.

I would swap one of the HL for an SL. Probably maths or chem unless you are completely a natural. You’ll need TOK too, right?