First of all, congratulations on your wedding and your special news.
I don't really have anything remotely helpful to say (as usual!) but the drinking thing could easily be disguised by sticking to Coke or lemonade - no-one will know they aren't 'proper' drinks, and getting your H (ooh! excitement!) to make sure that he is the one ordering the drinks. You could also, on the night, say that you've already had a few and feel a bit giddy and want to enjoy the evening - nobody will know any different. It'll be much easier to 'get away with' than you'd think.