I'd like to think that the British, unlike their American cousins, are efficient in their bureaucracy. That's why they sent one envelope (saving envelope and postage costs on the second) and one address (saving time, ink, and wear and tear).

Jolly good, my old man. Pip pip, as they say. Cheers to the missus as well.

Congratulations, I think. Love, B. M.

my only concern is that when your new country decides it's had enough and declares war on your native land, for which side will you take up arms? (Fortunately, they don't draft the blind and aged in either country until they're fairly desperate.)
Oh, and another thing, after you affirm/swear allegiance to the Queen, I hope she doesn't make you do anything ridiculous or very uncomfortable for her as part of your service, like sing to her while she eats.