Well, I was waiting for someone else more competent than me to respond to you.
So here we go.
Firstly, where in the world are you? You may have local regulations covering this.
I am in England, but the advice I give you may be of general help, wherever you are.
I do not think that you can divorce Heath and Safety completion from the general completion of the project. Google "construction completion certificate" - you will find any number of examples. The contract documents often contain an example format.
I think that the H&S completion is often by inference, since the Completion Certificate will often refer to the formal contract, and the formal contact will require the contractor to comply with all relevant regulations (i.e. including Health and Safety).
The attached example shows how one purchaser wants the process to operate (from the internet), this includes reference to CDM (see below) and to certificates etc)
The English Construction Design & Management (CDM) Regulations require the contractor to prepare a Health and Safety File. This is to be handed to the Client on Completion. There are items to be included that only come at the end of the project that must be included e.g. As Built Drawings, so the letter you send with the file (as a record that the file has been sent) could the Health and Safety certificate you refer to.
As always, it may be cheaper to review with your company's legal department before drafting a new letter, rather than wishing you had when you are in court!
