Posted: 04/06/2015 at 12:38
Thanks for the picture Susan - it does help!
I think I would prefer to see something akin to WillDB's suggestion of vertical boards (I'm thinking of feather boarding mounted on horizontal rails mounted on vertical posts) cut to give an even top and a stepped bottom which appears to sit on top of the wall.
I know it's tempting to try to gain instant privacy but I would not make the fence too high as it could feel quite oppressive. After the fence has been erected, I would consider Abi's suggestion and plant either a 'proper' hedge at the base of the wall and fence or (my own preference) an informal mixed tall growing shrub border.
This will eventually hide the join between wall and fence and any supporting posts and well chosen and well placed trees or shrubs will screen you from neighbours windows etc.
I would include a few fast growers such as buddleia, eleagnus, black and / or gold elder, amelanchier (airy, light small tree or large shrub), hazel and perhaps small ornamental trees such as crab apple and acer elegantissima. You could intersperse these with some slower growing evergreens etc aiming to get a range of height and foliage.
The fence will give you an immediate sense of increased privacy and the trees and shrubs will eventually give you more interest, and more privacy.