Protection from the elements: A 1 in 80 slope will protect even a flat roof from pooling of water that occurs frequently.
Extremely hot and cold weather protection: If you are having a new roof, or your roofing company are repairing a partial roof, ask if they can insulate it too. This will help your bills to reduce over the year. Ensure you ask that the roof complies with Part L of the Building Regulations.
Does it protect your home from high winds: An experienced roofing company should be able to offer professional advice on how your home is exposed to such an element, and may be able to give you honest recommendations.
Local authorities: You will need to contact your council or local authority when you have a new flat roof. This may depend on a number of circumstances, but speaking to them will help you avoid major issues in the future.