Confirm the hazard class first
The depth of the assessment and the renewal interval follow from the workplace's hazard class. The class depends on the activity code and is not guessed; read it from the hazard class query tool on this site.
Crowding changes everything
The width of a corridor, the height of a stair rail and the direction a door opens stop being ordinary details in a building where hundreds move at once between lessons. Evacuation time cannot be known without being measured in a drill.
Special areas
Laboratories, workshops, sports halls and kitchens are assessed separately from the rest of the school. Chemical storage, machine guarding, floor slipperiness and ventilation are asked separately in these areas.
People other than workers
The assessment exists to protect workers; but a school holds students, parents and visitors in the same space. If that population is left out when recording how many people a hazard affects, the severity score comes out lower than it is.
In Optifora
The risk assessment module gives this setting's hazard list as a starting point; you correct it with what you see on site, score it, and tie the control to a task with an owner. When the renewal date approaches, the reminder arrives on its own.