well allow a couple of days to do the Job, go around and break all keys the first couple / 3 hours Noting when they were turned off and after 3 hours start walking back around checking them, with the size of the school it may take a whole day to test the lot, and another day to prepare the snagging list and paperwork, you may well get some work out of it sso keep it tight, if you only got to worry about your wages then don't over do it due to the fact headteachers work in cluster groups of 6 these days as well, make one happy you may end up doing 6 haha.
Just clarify with them what paper work they want, if they want individual certs then the job is a different kettle of fish