I think everywhere in your photos was supposed to be where all the cooking was done.
Obviously it's all just a set (scenery) and not real - and space and budget is always an element, so we have use our imagination (or ignore the factors which tell us this is never going to be a real, efficient kitchen).
In Series Six, in The Odd Dog Men, we see some new cooking units of some sort being about to be installed in the kitchen, presumably in readiness for the completely redecorated cafe we see in the next episode A Bicycle Made for Three.
In Series Five we find out that there is a function room directly above the cafe - which seems to have been converted into a bedroom a few years later in Getting Sam Home - so we can assume there could also be room for more cooking facilities upstairs.
In Small Tune on a Penny Wassail, we see where Sid and Ivy live, complete with kitchen. It is not clear whether this accommodation is above (or behind) the cafe itself, or at a completely different address.