there are so many questions to ask: here are a few:
is this on a main road if so, traffic management needs looking into.
Can them windows with the barred balconies be cleaned from inside ?
is this just an out side clean and if so how often
some of the pics look like some of the windows would not be accessable with a pole so a cherry picker or such maybe needed.
do you have any experience in commercail work, what insurance do you have and does it cover hospitals (I see it is NHS) not sure if it is a hospital, I know for a fact that my liablity insurance does not cover us to work on hospitals, not sure why but I dont clean them yet some makes no odds to me.
Have you not thought about subbing this work out as looks a bit of a nightmare for a first job.
Dean T is your man
