For some reason, Building Regs fees do vary from area to area, but that figure is in the right range for a "Building Notice".
What winds me up in these cases, is that it's the builder's responsibility to liaise with Building Control, organise inspections, and receive the Completion Certificate. Why else would he be charging you for the Council's fees?
I use photos occasionally where I'm about to cover up an alteration forever, thus making inspections impossible. I would only ever do this after first asking my local Inspector if he agrees. In your case, an Inspector would be able visit and see the work easily.
Is there some nefarious reason for the builder not wanting it looked at?
The photo issue is irrelevant, Puss. The builder seems to be getting you to do some of the legwork that he can't be bothered with. Very unprofessional.
Incidentally, was a new opening created to fit the window?