I have just read through this forum and I can see that you have other issues that haven’t been touched on properly.
May I say that firstly you should not be contacting the HSE as they do not deal with such an issue as yours they only deal with issues that have resulted in loss of life or Extremely seriously dangerous situations which your situation is most definitely not and you shouldn’t be filling out the forms they do have a report form but that is not for you either.
The first thing you need to do is contact your local council private housing enforcemeant officer and file a report for not having any CP 12 certificate for your gas and you can further complain about anything else that your landlord is not doing so that they can investigate accordingly.
At the same time that you file the report to the council you should also be writing to your landlord asking for your EPC, CP12 & Electric Certification documentarian.
Please also note that it is a legal requirement that the landlord should hold at least the last two years worth of CP12 certificates.
You do actually have 2 issues, One issue is that you don’t have the other issue is that you never received at the beginning on or before the commencement of the AST.
You should be also then contacting the ICO and checking to see if your landlord is a registered data controller or not.
And if your landlord is that incompetent then I advise you to further contact the Shelter, CAB and the PSU as they will be able to help you further and direct you and possibly hold your hand somewhat.
There is also the matter of now needing to know if the landlord has the correct mortgage taken out on the property and the correct buildings insurance which should be checked because I would presume they would not be correct if your landlord is as bad as you state.
I hope this helps.