Rob
HSE as far as I know don’t’ have regulations re testing of electrical equipment, the have recommendations (so do it) they also have a lot more recommendations also do it.
Define test certificate (a little bit of paper stuck on a machine means nothing it’s the record in your files HSE will look at if there is a problem)
As far as I’m wear a competent person can do a PAT test with the correct equipment.
By the way I go over board I have them test every three months.
Len