I just moved 3 cats and 3 ferrets over the pond, and I can tell you, it isn't easy or cheap. From the east coast, it's best to go Newark to Heathrow on Virgin. The cargo crew were courteous and helpful. I was just looking at our female cat's paperwork. It was $332.36 to ship her - alone. (she got away the day of the other cat's flight) This expense is not including the vet, KSU, or the PA Dept of Agriculture.
I have a few pointers:
All animals must be transported in a container that is large enough for them to turn around. It cannot be so small that their back is skimming the top. It must have ventilation on all sides - even if you need to drill your own holes. Buy the largest container you can afford. You will feel better and so will the animal.
You cannot import more than 4 pets at a time without a commercial license. If you have more than 3 pets, you need to split the journey.
Virgin has climate-controlled cargo, so the animals made it though just fine, but I included a fleece for the ferrets cuz they like to cuddle.
Virgin doesn't allow a water bottle anymore - you must have the cups of water. No food prior to the flight -- and No Sedating Drugs prior to the flight or they will refuse carriage. I know - I have a cat that can't stand the car.. he meows and drools and sheds and all sorts, but once you hand over your pet to Cargo, he/she WILL be in good hands - they WILL survive the flight - and the Animal Reception Centre at Heathrow absolutely LOVE your pets as if they were their own - and feed, water, and cuddle them as soon as they are off the plane. No worries!!