Thanks for your replies! I have already spoken to Lenny and Paul from Petraveler, as they rang me back pretty much straight away and sent me prompt emails.
@Lisagail sorry it didn't work out for you in the US. You've certainly had quite a mammoth move, and doing it again!!! I moved from Italy to Australia in 2007 with 2 cats and a maremma sheepdog, and now am moving back home with 2 cats (not the same ones). It's huge. I hope it all goes well for you. I'm glad to hear that Petraveller were good. I worry a lot about my babies. How many stopovers did they have? And how did they cope, if you don't mind my asking.
@The Pom Queen what do you know of them?
Thanks!