G99 Type Test certificate

Is the the Gateway and AIO (6kW) certified for G99 and if so how do I get a copy to give to my DNO

Not sure if you can do this or not (or whether it needs an installer or someone) but there is a register where all certified equipment is held. You can search by manufacturer and equipment if required

For me the G99 confirmation of installation was submitted by the installer. This was what was listed in the confirmation

The ENA number is what you need I think. You can search them at https://www.ena-eng.org/gen-ttr/

This is the AIO GIVEN/13745/V1