Breakfast opens early on debarkation morning. 6am I believe.
A bit of a warning about the Kennedy Space Center tours - these have minimum guest requirements and are often canceled due to lack of interest. You may not know if your tour will happen (or not) until the last day of the cruise when they have to finalize the tour. On my cruise on the old Sovereign in 2008 I got a note delivered to my cabin on the last afternoon telling me my tour was canceled. That led to a really long and boring day sitting in the Delta Sky Club at MCO from 9am to 4pm when my flight departed.