It would be worth asking what is in your freelancers' contracts so that whatever you do is compatible with that. I am self-employed and my contract with my client contains terms to the effect that I will comply with their policy and procedures, and that the client will make these documents available to me. 

Some of these procedures of course refer to things that are provided to employees but not to freelancers, such as eye tests.  As long as these procedures say that such things apply to employees, there is no need to state explicitly that they are not provided to freelancers.

Your policy statement presumably makes reference to your intention to protect anyone affected by your business activities.  This should cover freelancers either explicitly or implicitly (along with other contractors, visitors, clients, members of the public etc).

The easy way to do this is just for each procedural requirement to be clear about who it applies to, which it really ought to do anyway.  Some will apply to employees only in which case you would just use the word "employees".  Others will apply to anyone working on your behalf or representing your business in which case you would use words to that effect.

The bigger difference in health and safety between the two groups you mention isn't their contractual status but the kind of work they do.  For example, if your freelance trainers are driving around to your clients, you will want them to adhere to your driving policy.  But your driving policy would be about any business travel on behalf of the company, not a driving policy just for freelancers.