16amp Cabling (30 meters) (Bellevue EH7)

Hello, I'm building a small workshop in the coal cellar above by lower-ground flat. I would like to find 30m of 16amp cabling to reach the space from the fuse box in the flat. The cable doesn't need to have 'commando' (waterproof socket ends) or it could perhaps just be the end of a drum of more conventional gray oval cable. It does need to be 30m however to avoid any joins. Many thanks in advance if you can help with this.