Time slots displayed

I am trying to set up a hall booking system with different time length options 1 hour, 2 hours, 3 hours etc., however when the time slots come up having selected two hours for example it only shows two hour slots i.e. 8am, 10am,12pm,2pm etc whereas I would like it to show every hour, 8am, 9am,10am,11am, etc.
Can this be achieved?