With the sun out in full force during the early months in Spring, now is probably the best opportunity for you to clean your conservatory and give the roof some long-needed algae removal treatment.
You first need to get hold of some algae removal solution, available in good home improvement stores. These products kill algae and will help make your task much easier. Apply the product whilst your conservatory roof is dry, with exposure to the sun. This makes it much easier to clean compared to when you apply the product on a damp surface, as the latter means more time to dry and clean.
After you have removed the algae, make sure to clean the roof thoroughly with water.