Even when there’s a totally capable other parent/ caregiver available, and you’re a feminist, and you’re bottle or mix feeding or able to pump, and you were completely convinced that your weren’t going to be one of those mums - it’s incredibly normal/ common to not want to leave your young baby for any length of time.
Im sure the father would be perfectly capable.
It may well be that OP feels totally comfortable to go ahead when the time comes, in which case more power to her.
But these threads always follow a pattern of - lots of women saying they’d have found it difficult to do and warning the OP just to be prepared that they may not want to do it when the time comes - one or two extreme/ judgey posters will say it’s cruel or unnatural or whatever - then the judgement almost swings the other way and lots of posts about ‘not being able to understand’ why anyone would find it hard, implications that you don’t trust the other parent/ picked a useless one, and probably sooner or later scorn being poured on ‘mummy martyrs’.
It’s fine, and very normal, to want time away and great if you feel you’re able to enjoy it when the time comes.
It’s also fine, and very normal, to not want to be away from your newborn for any length of time and to not be up for nights away even when other people think you should be ready.
In the OP’s position I’d be wanting to wait and see how I felt nearer the time. I’d probably book it a little closer to the actual wedding date, not let anyone pay to cover my costs as I know sometimes happens, and as it’s only 5 minutes away you could maybe book but with the proviso that you may stay there at night, or you may head home and hopefully everyone will understand either way.
Also - don’t get too bogged down in ideas about what your ‘proper hen’, wedding, honeymoon etc should be like - it’s going to be different with a baby, but equally wonderful. I was pregnant for mine - shit timing in some respects as I was feeling knackered and sick, trying to keep it a secret from so many people and incredibly anxious because we’d had some scares along the way. It maybe wasn’t what I’d pictured in some respects, but that’s what we signed up for knowing we were going to continue ttc in the run up to the wedding. Even though it changed quite a few aspects, it also made it extra special as I’m sure having your little one there will for you OP.