Silks 
I have done that too, had an attack of the wobbles and halfway through have suddenly thought hold on I am overstating it a bit, things aren't actually that bad. Of course I can't admit that at the time so I soldier on bravely.
Maisy I agree you have numerous reasons not to want to be entertaining strangers. I think there are times this can be fun and interesting, and you come across people you might not normally meet, etc etc but I don't think post-hospital, a small baby, and Christmas looming really make this one of those times. Normally I'd suggest offering to do something else instead, eg offer to bring them somewhere or show them around or something but I think you'll want to be free to tend to ds. I hope it goes well for him, and that dd2 is ok too. I'll be thinking of you.
Santa hope your dd2's temp went down and you've not had a trying day.
dp's car buggered yesterday, just stopped dead on road home. Abandoned, and towed this morning. Feck.
Santa Claus was at playgroup this morning, ds's greed overcame his fear - he tiptoed up to him all shy and suspicious, but rapidly swiped the offered present and made a getaway. (Each person brought a little parcel beforehand.) It was quite sweet really. It's a nice group, but a bit too big.
Oh. rambling.