It just needs to be a simple letter, don't make a mountain out of a molehill.
My name is X. I am writing in support of the application for settlement visa of Y.
We met blah blah blah
She will reside blah blah blah
We plan to marry on such and such date (if you have a date confirmed with a church or something I'd include that).
I'd type out what Alex wrote.. but it's at the NY consulate at the moment
