I work in a close team, we've all been there many years and are all friendly and get on well. Lovely people.
Over the summer DP and I are having a statutory wedding to get our legal affairs in order. My colleagues know we aren't married - it's not something I go on about but it's come up in conversation over the years. On advice from other colleagues in our firm (legal sector) DP and I realised we needed to sort things out.
I wasn't going to tell anyone - other than my parents and the neighbours who will be witnesses, I haven't told anyone but MN 
- but it ended up coming up in conversation at work as there was a big professional project that would be delivered on that day, and I had to say why I really couldn't be in the office that day. No big deal, I'm not embarrassed about it, but it's not something we are remotely making a fuss of.
Since then it's been questions, questions, comments all the time... "Are you changing your name?" "When's the hen do?" "Surely you're having some sort of party?" "What night shall we arrange to go out then?" etc etc
Bless them, I know they mean well but no, I'm not having a "wedding", no, I'm not having a hen do, and no, I'm certainly not changing my name...
It's starting to annoy me now, no matter how much I keep politely saying "no" to all their questions and not talking about it, they won't stop talking about!!