I would say 1 person 3 days to do a good job.
From the pictures, the cladding doesn't look too dirty, so either wfp, or if you have the pressure washer, it probably would shave a bit of time off. The poly sheets would probably be a couple of hours, at least they are not glass!
I would also if its just a one off, quickly scrub and rinse the frames so they are clean, then go behind and traditional the glass.
I have found that some older schools that we clean have had anchor points fitted, worth asking the main contact to find out?
As for price, i would base it on your day rate but plus a few quid more per day as its a one off.
I would price around a bag of sand Matt.
