Lloyd, that is a JOB, not a one off.
SAJ, it looks a nightmare and you will hate every minute of it! Charge £200 and hope they fall over. If they say yes, at least you will know you have a good days takings.
There will be leaks all over the roof beams into the conservatory if you use WFP or pressure washer.
The paintwork will make a mess of your WFP brushes and you will need a conservatory access ladder to access the roof area safely.
What a disgusting condition by the way.
Do that for a £100 and you are certifiable!