I always thought that the cooking area seemed rather small. From inside the cafe the cooking space seems alright. Yet trying to visually measure things up from the outside shots the cooking space seems shrunk, or too small. I know it is television and they have to be creative with what space is available.
Apparently there is space for cooking as well as a stairway to the next level up. As mentioned when Ivy was upstairs and says she did not hear the bell in one episode. Also for the Bollocks guys to go up there to the area where they had their meeting. I believe in the real shop the counter is along another wall, as mentioned.
Yes, some of the shots through the window the wall seen opposite appears closer in some episodes than others. Probably the studio versus location shots. Or something going on outside and they made a fake wall screen to cover it. Oh how the mind wanders at times, at least it keeps us busy.