Becoming an expert in ISO 45001

Answer:
The best way to become more well versed on ISO 45001 is by using it. I would recommend going through the standard and working out for yourself how it would be implemented for an organization. Probably the 2 things that you would need to study for the particular teaching organization that you want to be an expert for are the legal requirements and the OH&S hazard and risk assessment.
Knowing the legal requirements that an organization needs to meet is very often specific to the organization at the location indicated. Likewise, understanding the processes of the organization, as well as the hazards that these different processes can present for workers, is a very specific skill that the OH&S expert in any organization needs to master.
For more on complying with legal requirements, see this article: How to identify and comply with legal requirements in IS O 45001, https://advisera.com/45001academy/blog/2015/06/24/how-to-identify-and-comply-with-legal-requirements-in-iso-45001/