You can block out a diary using all the bookings in a planner in the following way:
Edit the relevant planner from the left hand window by clicking the planner using the right mouse button and selecting Edit from the context sensitive menu. The Planner property sheet is displayed. Select the Diary page.
Select the diaries that you wish to block out. You must have at least create access to each diary that you select. Select the Block out associated diary check box and press OK.