Do I need an expansion gap around concrete laid inside a building
Concrete has about the same expansion rate due to temperature as steel [this is why reinforced concrete does not break apart from thermal stress]. A stone walls are likely have another coefficient of thermal expansion (and perhaps some other constraints).

It is sound practice to isolate  slabs from existing structures absent a compelling reason to tie them together. A compelling reason would be structural necessity. Apathy is at the other end of the scale. Other reasons, may fall in between but generally toward the non-compelling end.