Scafolding wouldnt be that expensive for the rear especially if you see a scaffoding company out and about and ask if they would do a cash job.
I pay about £250 cash for 3 landings on my gable endever couple years to clean algae/moss of top end render that was supposedly self cleaning and free from lichen.
Cleaning would get them looking as good as new from what I saw when my neghbour had his done. However it doesn’t harm getting a price for both new or clean and go with whats best. The company who did my neighbours also jetwashed his roof and applied a coating, which i don’t recommend as it will look like it hasn’t been done within a few months.