Cheers guys.
The flue runs from the 1st floor cupboard, up through the ceiling into the roof space, then along a bit and then up to vented ridge tile on the roof. Not sure if the whole flu is asbestos or just some of it, although the whole thing has to come out.
It's going to have to be a pro job though. The father in law has asbestosmosis, so they're fk'all chance of my Mrs letting me anywhere near it!
Have a put a call in to a local remover, so hopefully get an idea by the end of the week. Hopefully wont have to sell a kidney, otherwise we'll just have to be cold for a while!