Hey, i went through this at one workplace when i (a female) was dating my now ex girlfriend, and had to keep refering to her as my partner and trying everything possible not to say he or she! I could never of told the people i worked with there though, they were so clicky...In the end, i told a supposed friend who worked there who i thought was a pretty good friend, I left that place a couple of months later to find out she had told them anyway! I agree with the other 2 answers and that you should just mention your partners name in conversation and say how they will have to meet her...or maybe even use your ceremony as a chance to tell them and ask them to come out for a few drinks after?
Hope it all goes well :) x