Firstly, I am very pleased for you that you are expecting your first, so, many congratulations @Kittycat02
But regardless of the wedding, 8 weeks is really too early to tell people, in my view. So many things can go wrong in the early days of a pregnancy, which is why most people wait until the 12 weeks scan, 'just in case'. It's really hard on the couple concerned, to tell people that they already told you were pregnant, that actually, you aren't any more.
Just wait would be my advice. That way, you are protecting yourself as well as not running any risk of possibly taking the spotlight away from the Bride and Groom AT ALL. Although I personally wouldn't feel like that if I was them, I understand that is how some Bridal couples would see it.
Metronidazole is an antibiotic which comes with very, very, strong warnings not to drink alcohol while on it, or it could make you very ill and it is prescribed for various things. I am prescribed it occasionally for digestive issues, so I don't agree with people here who say people will know if you say you are on Antibiotics, that you are pregnant. But PPs have given you lots of suggestions as to how to disguise the fact that you aren't drinking alcohol as well.
Enjoy the wedding and hope all goes well for the future, with your baby