There are two parts to the theory test: multiple-choice and hazard perception. The tests can normally be booked for the same day (subject to availability) or taken on different days if you wish. Both parts must be passed before a practical test can be taken.
To pass the multiple-choice test, you must correctly answer 85 of 100 questions in the allowed time of 2 hours. The answers to all the questions are contained in the book, The Official Theory Test for Drivers of Large Vehicles.
The topics covered by the theory test are:
Vehicle, weights and dimensions
Carrying passengers
Accident handling
Leaving the vehicle
Restricted view
Environmental issues
Drivers' hours and rest periods
Attitude and alertness
Braking systems, speed limits and overtaking
Safety and hazard awareness
Vehicle condition
Vehicle loading
Windy weather and heavy rain
Traffic signs
The hazard perception test consists of 19 film clips (18 clips containing 1 scoreable hazard and 1 clip containing 2 scoreable hazards) of real road scenes containing potential hazards.
When watching the clips, you respond by clicking the mouse button as soon as you become aware of a hazard. The pass mark is 67 out of a possible 100 and the allowed time is 45 minutes.