You will see them mouthing fake conversations, pulling fake files, scribbling imaginary diagnoses, and generally trying to move about like people in a hospital do. They are, however, not in a hospital.
Gervais asserts that he plays a character on stage, ironically presenting himself as better or more knowledgeable than the people in the seats. But it's a bit harder to laugh along with the school bully than it is with the class clown.
Gervais and his co-writer/director create one premise, then seem to shift to something else - and then to something else again. But the conceptual problems are less troubling than the essential shortage of laughs.