Having to get two children ready and packed for the GPs is a walk in the park for any experienced parent surely? I must have done it a hundred times, on my own...The dog could have made do with a brisk 5 minute walk round the block, just this once?
Chances are he'll be fine to drive in the morning, but if not could your inlaws not have the dog for once? There's no reason why you can't drive to the wedding is there, anyway.
In your shoes I'd take the DCs to their GPs. Get myself ready for wedding, and relax while he stumbles around, getting ready, feeling like shite. I'd probably make several caustic remarks, but leave it at that.
I certainly wouldn't spend the day seething and punishing him because that makes for a pretty crappy day all round. If he's generally a decent DH the vast majority of the time, then the occasional rubbishness can be overlooked, I reckon.
Missing your night out, I don't get? Why did you agree not to go? If he said he'd only have a couple of drinks, then come back to let you go out, then, yes, that would piss me off.