Even when you are fully productive and driving you don't have total freedom of when you can take holiday as it is rostered in blocks. you may be able to mutually swap your block with another driver, but demand for school holidays/christmas is high. You will have a number of days ad hoc which you an apply for as you wish, subject to a maximum amount of drivers per day on leave.
You will get leave during your training, but only when it is convenient to the company in your training, but they will not let you run off on holiday in the middle of your rules course or traction courses.