The main government reference you want is the GOV.UK fire risk assessment guidance, which says you must carry out and regularly review a written fire risk assessment, and it explicitly covers workplace premises such as garages and workshops.

Useful reference

  • Fire safety in the workplace: Fire risk assessments — GOV.UK.
  • It gives the standard 5-step process: identify hazards, identify people at risk, evaluate and reduce risks, record findings and emergency plans, then review regularly.
  • It also says to consider escape routes, fire detection and warning systems, firefighting equipment, evacuation planning, and vulnerable people.

For garage workshops

A garage workshop is usually treated as a workplace or workshop-type premises, so that GOV.UK guidance is the right starting point. The guidance also points to use of standard fire safety risk assessment guides or a competent person if needed.

Exact wording to search for

If you need the document name for a form, policy, or citation, use:

  • Fire safety in the workplace: Fire risk assessments
  • Fire risk assessment checklist

Practical note

For a garage workshop, the assessment normally focuses on ignition sources, fuels, storage of flammables, electrical equipment, welding or hot work, housekeeping, escape routes, and fire extinguishers. Those specific hazard areas fit the GOV.UK framework, even when the document itself is the general workplace guidance.

TL;DR: The best government reference is the GOV.UK workplace fire risk assessment guidance, supported by the official checklist.