I'd agree with self-catering. Ask for stairgates etc. in advance and keys for any locking internal doors. No harm in asking!
If you have any special dietary requirements you can usually get info in advance - I got onto the FR equivalent of the user group for my daughter's condition and they told me (very kindly in English!) what dairy-free brands to look for in the supermarket.
Suss out the local hospitals online. Depending on where you are going, it may be a lot faster to go to A&E yourselves than call an ambulance.
Order nappies online from a local supplier for delivery to the villa before you arrive (obv talk to the owner up front but they will be fine with it.)
Strongly agree with setting expectations re: sharing care responsibilities.
Flying: where do I start?
- Airline's Disability support varies but they all have a customer services rep whose job it is to sort your requirements. Phone them waaay in advance and discuss. They should put what you need on your booking. However, every person you meet through the airport will fail to have read this so be prepared to repeat your story at checkin, security check, gate, boarding etc.
Try to get seats pre-allocated before you checkin: again this is something customer services should do for you on the phone but can only do when the computer "releases" the seats for allocation which is a variable amount of time before boarding depending on the length of the flight. You may have to call 3 or 4 times before the trip is completely arranged.
Alas, you can't pre-checkin on the internet with most airlines if you are travelling with children. One reason is that they can't distinguish where any infants will be sitting and in some airplanes they need to sit on a specific side to get the extra air mask.
- meds. Airlines will carry anything that is legal in the country you go to as long as you have a) a prescription and b) a doctor's letter saying you need it. You may still hit the 100ml liquids restriction - in theory BAA policy is to let necessary meds through but in case you get a jobsworth on the day, pre-order in 100ml bottles and split between the party's hand luggage.
- small distracting toys for the journey: finger puppets pack up small (£5 for 10 from Ikea) colouring sets etc. Ration them out, including some for the way home. Not that DD1 gets any of the above, but it keeps DD2 out of her hair.
- wheelchairs can be a nightmare. It's OK if a standard adult wheelchair will do you, but if you need restraint/support/small size it's a fight. Airport regs differ and some places simply won't allow your own in the airport because they can't security check them. It's worse if it's a SN buggy because they really don't "get" the necessity. UK airports seem OK, European ones variable. New EU directive (comes in in June) means that if you put your requirements to the airport in writing to arrive 3 days before you do (obv need names, flight details etc.) then they HAVE to do what you ask or provide equivalent support. Hally bluddy lulia - carrying a 4 year old from the plane to the baggage carousel is no joke.
I get "this buggy is actually a wheelchair and needs to be put in the correct hold section to be delivered to the gate on arrival" translated into the local language and printed on a card. Then you can shove it in the faces of the people who take it off you at the gate and they have no excuse they don't understand you. It also helps to put the buggy in a carrying case and then print/laminate a large offical-looking blue "wheelchair" symbol to attach to it.
However, the only person who can actually ensure your wheelchair is delivered to the gate on arrival is the purser (head steward/ess) who asks the captain to radio ahead to the airport you are going to. Befriend them and they will have the arguments on your behalf.