Sunroom/conservatory in L shaped sidereturn

[swanriver]

Has anyone built a sunroom into L shaped sidereturn/alley of a semi-detached terrace and lived to regret not knocking through outside walls?
We have diner and kitchen already, which we don't want to radically mess up, just wanted to add a sort of glass covered porch area 2m x 3m and keep existing structural walls.
Faces north east so quite dark except early morning.
Pros and cons and experiences please.

[ampere]

So how would you access this new room? From outside only?

What will you use the room for?