has anyone used any particular training courses / providers to transition across from OHSAS18001 to ISO45001?  I didnt attend any training before taking my company through 18001, but would like a solid understadning of the new standard, and understand what we are potentially missing, before taking the company through a 45001 audit....any help ?

We went straight to ISO45001, no training, nothing.  As a Chartered practitioner, I looked at the system and Annex SL, then determined the additional elements that would be needed to the existing ISO9001.  If you understand the Annex SL and what is required under the 9001:2015 version e.g. PESTLE, SWOT, Needs & Expectations, then you can add the 'Occupational Health & Safety' aspect to these.  

Your basics for risk assessment will be extended to identify Opportunities for Improvement and you will probably have a 'Business Risk Register' - but as for training, I think its not really worth it too much.  You need to consider the auditing and 'leadership' area - how does the Senior Management Team display leadership in Occ H&S?  Its interesting to formulate a system, to which we now have an IMS, with 1 NCR outstanding (we hadn't had the 2018 Management Review by the 24th Jan), so thats one for closure in Nov 2019.

Drop me a PM if I can assist.