I feel like I have discriminated the old slates! Nothing else is wrong with the roof apart from one or two slipped slates. After finding more information on this I think we can fix this without too many problems.
Many thanks for your comment and tip on the slates.
:D
A property I am in interested in buying has felt roofing on the kitchen extension. The rest of the property is slate roofing and a few due to the high winds have slipped (the slates look pretty old too). As I cant even be described as a novice in this area I would be greatful on any information...