Don't know boiler model at the moment if this info is needed, it also
>looks a few years old so may update with a new one if needed.
If you've got a lot of fluing involved, seriously consider the Keston Celcius. Although it costs more than many boilers, this is easily offset by the fact that it uses 50mm drainpipe for the flue, costing pennies, rather than hundreds upon hundreds for large proprietary flue extensions that might have difficult fitting up a chimney.
BTW, I'm thinking of doing just this for my cooker, except without the boiler complications. I was going to use multiboard rather than aqua panel. It is the modern equivalent to asbestos sheet. I had to widen my chimney out though. It was 89cm wide and the cooker was 90cm. :-(
Christian.