The team is MI-13 now. Excalibur takes her code-name from the sword.
Military Intelligence (Section) 13 is "hypothetically" real, even though the British Government has only ever admitted to the existence of Military Intelligence as high as MI12 and most of those specialized arms were burnt off after WWII.
MI13 the comic, disappeared a long time ago.
Captain Britain is the headmaster of a school named after himself, and he's probably spenidng most of his time trying to talk Meggan into making more little Braddocks but she's sad that she can't make any Wagners.