I have fitted the film for a few years now, on behalf of the local council as part of a child safety initiative, ...
If your builder has'nt fitted the film before I can tell you now it is more costly for a roll of it, than it would be for a piece of 6mm laminated glass.
One tip I will give is put a spot of Fairy liquid in an atomiser and half fill it with water, and spray the glass with loads of liquid.... more than you would imagine...it just allows you to push it around ... before using a sqeege to press it home.