Anyone whose work could disturb the fabric of a building built or refurbished before the year 2000, where asbestos may still be present: electricians, plumbers, joiners, roofers, shopfitters and general maintenance and refurbishment trades.

Asbestos fibres are invisible in normal use and cause lung disease that can take decades to appear. There is no known safe level of exposure, and disease from past exposure still causes thousands of deaths a year in Great Britain.
This pack is awareness training only. It teaches people to ask for and read the asbestos register before starting work, to presume asbestos is present in a pre-2000 building where no register exists, and to stop, leave, prevent access and report if anything is accidentally disturbed. It does not authorise anyone to carry out licensed or notifiable non-licensed asbestos work, which is reserved for a contractor holding the relevant HSE licence.
One hazard, done completely, for the whole firm.
The pack also has a theory test answer key. It is supplied separately to the employer, not published in the pack itself, so the test stays a genuine assessment when your own supervisor marks it.
Not required to be compliant, but available where a customer, principal contractor or insurer wants third-party evidence.
You assess your own people in-house using the pack, and send PHW the completed records. PHW checks the records and, where they hold up, issues a certificate carrying a QR code that resolves to a live verification page. The certificate states plainly that the assessment was carried out in-house and verified by PHW. It is not a record of PHW having carried out the assessment itself, and records that are too thin are rejected rather than certified.