Im not going to guesstimate an answer to the cost question (sorry), but i will take the liberty to harp on a bit about the triple glazing:
The primary advantage of triple glazing is that it will be a few degrees warmer on the inner face than double glazing. This has a considerable effect on the comfort in a room (esp if you plan to hang around near largish areas of glazing) and could well mean that you feel happy to turn down your heating by a notch, as opposed to up by a notch when you feel the 'shiver' effect of being near a cold surface.
On the heating, you are mixing a constant low heat source (heat pump) with a sudden high heat source (stove). Please make sure that everyone (architect, plumber, yourself) is clear how these two sources will work together in order to maximise efficiency.
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