I have a uPVC conservatory with polycarbonate roof. Is there a chemical cleaner that can get to hard to reach areas and get rid of green stuff without having to use a pressure washer? Ideally, something I could spray on and then hose off???

Any Thoughts?

Conservatories are my business, and I have occasionally had to do what you are asking. I'm afraid there isn't any easy solution. There are special ladders which have a cranked join, which allow you to set the ladder up to the gutter, and then slope up the roof. I don't know if they are available for hire though. However, if all you can get is a normal straight ladder, get yourself up to gutter level, and then it's a case of an extending pole brush and warm soapy water. You can get rid of most of the dirt, and then sluice down with a hose. I did do one where I actually de-glazed the panels, took them down one by one, cleaned them and then re-glazed, but you would need to know what you're doing. The other thought that springs to mind is the possibility of changing the panels. Ideally you would replace with glass, which can be self-cleaning ( Pilkington "Activ" glass) , but you could also replace with newer and much improved polycarbonate.
This post is exactly why I never recommend the use of polycarbonate - it's noisy when it rains, gets dirty, and you can't see through it. The problem is that it's easier and quicker to fit than glass, so fitters prefer to use it.
If you also need to clean down the ridge cover,and cresting if there is any, then you DO need the special ladder. This is another reason why glass is best - you can use sucker pads to get a safe seat up there while you do the work.