You will often see the description "dining coach"
The great cabin (in an English Man of War) would be the absolute private space of the captain, and would normally not have a long table to accommodate the whole staff as seen in the movies. There would rather be a desk, several armchairs for guests, and a lot of walking space.
A large table can be rigged there for formal dinner parties, but that is not the normal state.
Typically in front of that would be his bedplace (on Sb), with a cot, and the dining coach (on Ps), with a table for maybe six guests. That is also handily close to the captain's pantry, which in many cases will be one deck below together with the wardroom/gunroom pantry.
I have never seen a drawing with a corridor between the coach and the bedplate, so one assumes that it is also the entrance to the cabin, where the marine sentry would stand just outside.
on some ships, small arms racks may be there for safe keeping, and the table would have to share the space with a gun or two, likely stored fore and aft on the side.
In Lavery's book on Bellona, the coach is labelled lobby, and there is a small adjacent cabin for the captain's clerk.
Note that usage in other navies tend to make the great cabin less private, and accessible by other superior officers or distinguished passengers, particularly in single deck ships where the gunroom is a not very welcoming confined space. Think for instance about access to the heads in the galleries, one for the captain, do officers have access to the other?
