I would say it looks like a 2 hour job tops.
I would also say £75 is too cheap.
You live and learn!
Yes will live and learn ... But know way would it be two hours the second time around, maybe 4 quickest (one man)
Also the was more lichen on the before picture by the plasic top roof finnals, but never took photo before i started,
The photo with bad lichen was also like that on the photo with the plastic finnal run.
Anyway two hours for you thats great, i would have been happy with my price £75 at that time scale.
I scrapped with 6" squeege channel to the best then followed with a scrubbing brush , i have do i roof this size before in about 1 1/2 hours without much lichen.
I have so many adapters even made my own fitting with my metal lathe and milling machine.
The was not much else i could of made to help make life easier.
Could have to my portable scaffold tower, but was leant out, this would have be good to look down on the job for more pressure, Felt like getting my hard surface cleaner and gx390 pressure washer on it, blast the roof of.
Should of pulled the panels out, steamed the off