Hang in there sweetheart, as my ol' grandma used to say (she had loads of kids and no washing machine) they don't always stay 6 months You'll get through this and maybe you'll even enjoy running the show alone for a few days.

Take the eldest out of daycare for a few days (it won't leave a dent on his future CV)
Make sure you've got all your groceries and goodies before his big trip
Make sure you've got doctors who speak English
Find a babysitter, if anything just to come over for tea and a chat

What you're missing is an infrastructure to count on.
Stay tuned to EF, and we'll see ya through !