I didn't change my name. My son has his father's surname.
People nearly always address things to Mr & Mrs X. This doesn't bother me, people are just lazy. IDGAF
People always ask, even my husband, if it bothers me that we don't have the same surname. If it bothered me, I would have changed my name. But I have a name, I like my name, why would I change it?
We are no less of a family just because I have a different surname. Plenty of other countries don't expect women to change their surnames when they marry.
My parents are unmarried (they've been together 40+ years.) so I don't have the same surname as my mother, pointing this out to people is hilarious because they nearly always have been slightly rude beforehand about the surname situation so get a bit embarrassed about being a dick.
The only thing that does worry me is how travelling with my son without my husband will be. I guess I'll just travel with copies of everything, but it's still ridiculous. I frequently travelled alone with my mother when I was a child (internationally), even before she became a British Citizen, and that was never a problem. But I fear times are very different to when I was a child.
On the upside, not having the same surname means that people don't buy us lots of personalised crap with DH's surname on it.