The main door, with what looks like an aumbry to the right.

This is a small cupboard, generally on the north side of the sanctuary
(so I'm not quite so sure what it's doing here, in the north aisle -- although I did spot obvious ones to the north of the side chapel and main altar...!).
Its use is a little confusing: when Anglican churches returned, with some enthusiasm, to the practice of reserving the blessed sacrament in the late 19th century,
aumbries were used, and in some cases built, to contain it. A light burned outside the door of the aumbry to denote the presence of the sacrament.
However, there is some evidence to show that the aumbry had a different purpose in medieval times: containing those objects considered sacred rather than just valuable.

From the New Advent -- Catholic Dictionary -- website;
"Variously written AMBRY, or AUMBRYE, [aumbry] is a derivative through the French of the classical armarium, or medieval Latin almarium.
Its original meaning was a cupboard and it has never lost this more general sense, but even in classical Latin it had acquired,
in addition, the special signification of a cupboard of holding books....

"In German the word Almerei, a derivative of armarium, has the meaning of sacristy."