Hello,
I use http://www.roombookingsystem.co.uk in my school.
It handles Bi-Weekly timetables.
you can enter in the holidays so it shifts the correct weeks about,
it only displays the free rooms and in a timetable view,
change one option in the admin panel to make all new bookings provisional so an administrator has to check them,
can set it up so teachers can only book x weeks/months in advance,
its perfect!