Thanks for all the info guys, lots of comments and advice on there, much appreciated.
I think the scraper is out for me as it looks proper tedious. Pressure washing better option no dou,bt but i think only on certain jobs where you can gain access via a cherry picker or spider lift, as Darren said (dont want to be clambering on top of roofs for sure). Might leave it alone for now!!
Darren, do you have your own spider lift or hire one, what sort of cost to hire? and do you need a licence?
cheers