If it were me, I’d go for the wedding and leave after the ‘breakfast’. I can’t stand wedding discos - or at least all the ones I’ve experienced have been deafeningly loud, with nowhere to escape to.
Not long ago, 6 of us (all related late 60s/over 70s) attended the church bit and the afternoon tea (it was the wedding of a cousin’s son) but left before the late dinner and disco. We went off for a nice quiet dinner together, close to our hotel.
Of course we informed the couple in advance, so they wouldn’t be paying for wasted meals, and I’m quite sure they weren’t in the least put out by half a dozen oldies buggering off early - there were plenty of their young friends for the later revels.
Might add that we had a very nice and unusually prompt written thank-you for the cash I’d put in the card!