You and your landlord must come to an agreement for the holiday period. If you are permitted to use the room, the property owner is permitted to charge a 'daily rate' equal to 1/31 of the monthly rent.
The period during which you must have a room for examinations for the exam period in August or September is clearly stated as beginning 5 days before the start of the first examination until the day after the final exam. Precise written agreements can be made based on the exam schedule.