Trislander,
sorry if you found my reply a bit 'robust'; it wasn't meant to be - but your post did come over as though you were planning your elevation to Capt and wondering how you would change the headed writing paper from chez Tri!
In UK, perhaps more than the US, the use of a professional title, other than Doctor, outside the place of work is somewhat frowned upon by society. You may speculate on the UK society's love of mediocrity and its reluctance to celebrate success as perhaps the reason for this, but it is so. As a result, we tend not to use our title outside work - even our own people sneer at the 'vanity' of those who do style themselves Capt. Bloggs in civilian life. Even Knights and Peers of the Realm are now somewhat coy about their titles, usually earned by bloody hard work in some field or other.
It's interesting to compare this with, say, Italian society in which one is expected to wear one's professional title with pride - witness the prefix 'Ing.' for engineer.
Discuss, with examples....!