The Home, End, Page Up and Page Down buttons can be used to navigate around the booking screen.

Home and End

The Home Key can be used to go to the first available time which can be booked in the current column.  The End Key can be used to go to the last available time which can be booked

Page Up and Page Down

The Page Up and Page Down keys can be used to move one screen at a time.  This provides a quicker method of moving between the times in a column.