G'day Aviast
In Australia the Cert IV is OK if you want to be, and remain, a "safety officer". All the Cert IV qualifications are basically a "trades" certificate. If you are involved in dealing with the paper cuts and the bad backs, worker's comp etc then this is a good place to start.
In the mining industry you'd never get a start in an OHS role without this as a minimum.
When you have your B.Sc(Av) you could possibly consider the OHS program (Graduate Certificate- 1 year or Masters -2 years) at Newcastle Uni.
I suggest you will need much more than Cert IV to move up the ladder, but aviation "safety" decisions never cease to amaze me
PM me for more info on the Newcastle program.