Conservatory in awkward area

[Snorkerz]

My kitchen is part of an annex which takes up 70% of the width of our property. My neighbours property has a similar layout which means we both have a (approx) 1.8m alley between our kitchens and the relevant neighbour.

I want to build a conservatory-type extension to my kitchen in this area, occupying approx the 1st 3m. This would have 3 existing boundaries, 2 being ours (2 storey) and one being the back of the neighbours kitchen wall (single storey with gutter).

Because the area is so narrow, I don't really want to lose any of the width, so does anyone have any good suggestions? Really I'd like to use the existing neighbours wall and ultimately have it plastered to become an internal wall (after all the rest of the house shares the wall) but I am guessing the conservatory roof will need to be supported off that wall, which I guess was only designed to hold it's existing roof.

Alternatively, I could build a windowless UPVC conservatory wall alongside the existing wall, but would the lack of air circulation between the walls cause a problem? I'd rather avoid this anyway as I'd like to mount kitchen wall cabinets on that wall.

The current details are here [url]http://www.snorkerz.com/images/1.jpg[/url]. In this image, the 3m point falls between the window & downpipe on the right hand side.

Any ideas appreciated

Dave