I went out 'clubbing' (ie. mates' band were playing in a club) when dd1 was a week old, leaving her (& a big bottle of expressed milk) & ds with MIL.
We arrived about 8pm, left about midnight - just after the band we'd gone to see - I was knackered & my boobs were leaking to a degree that was just too uncomfortable to stay out later.
It seemed, & still seems, like a perfectly sensible thing to do.
Dd1 hadn't actually woken the whole time we were gone, but if she had, I really don't think she'd've been any more traumatised than ds was at a similar age when dh fed him a bottle of ebm because I was asleep - ie: not at all.
& we could've been home in 30 minutes, max, if we needed to be.
We're all different. I found pregnancy absolutely ghastly, but the first few weeks of motherhood a doddle - babies who tok instantly to bf & were also happy with ebm whilst I bounced back & was ready for a night out more or less straightaway.
Wouldn't've gone for a mini & thigh boots, but frankly, bloody good luck to any new mother who would!