Wow! Very nice! I am actually about to do something similar. Here in the States they call that style a "Monitor Building". I will keep an eye on progress.
The one I am looking at looks something like this. It would be clear-span, so no columns inside. I was actually surprised at how cheap the building itself was quoted. But then of course you have to factor in the erection, sparky and plumber, doors etc so still weighing all against conventional construction.
