Is it feasible to maybe just go for the wedding, rather than the whole night? I guess it's still a couple of hours of driving, but it can be nice to get out of the house while you still can - from what I hear the first few weeks after bubs arrives can see you pretty much housebound..

I'd be reluctant to say yes to the RSVP & then not turn up, just because weddings can cost so much per head, & they might have a couple of other people who weren't on the first list that could be invited instead, and that way you won't feel bad.

Good luck with it all