Fellow DVC/Saratoga Springs-er and Yankee here, and mother of 7 who has taken <1 year olds to both Europe and Asia many times.
Here's my list for the big flight...in addition to all the normal stuff like diapers (you call them nappies, I think) wipes, spare clothes for you and baby, snacks, small toys, etc.:
1. Request a bulkead seat with a bassinette (I think you Brits call them cots or mini cots.) They work great so long as your baby still fits in them. Even if baby is too large to sleep in it, though, they often still find it a great place to sit and play, which gives your arms a nice break. Nearly all transatlantic flights and all classes of service have them, but sometimes there are only one or two, so be sure to get your request in as soon as you can--before some other intrepid traveller can get it first!
2. We keep ear numbing drops (the label says "Antipyrine and Benzocaine Otic Solution USP" whatever that means

) in the diaper bag, which work very well if your baby seems to be sensitive to altitude changes, but they do take some time to work, so don't wait until you're on the way up to put them in baby's ears. If your baby is breastfed, she or he can nurse on the way up and down, too, which greatly eases any discomfort. If not, I hear having a bottle ready works pretty well, although you can end up in trouble if you give the bottle too soon and run out before you get in the air! (All the airlines can warm a bottle or baby food for you.)
3. This is very controversial here, but on our pediatrician's suggestion, we always give our littlest one 1/4 to 1/2 teaspoon (I think that's about 1 to 3 ml?) of Benadryl (also sold as diphenhydramine) about 10 minutes before the flight. Baby usually sleeps well for up to six hours as soon as the benadryl kicks in.
4. Not really for the flight, but if you and your sweetie want some "time out" without baby while in Orlando, I highly recommend the Fairy Godmothers' service. Our children have always had very good experiences with them!
If you have any other questions about how we manage things, feel free to PM me!
Michelle