Here I am posting in case you haven't found your answer yet -- with any luck, you have!
My wife and I flew our cats through the PETS Scheme from Houston to London Gatwick on December 2nd. Houston is on the approved DEFRA list, but only if you fly out on Continental. That would have been perfect, except that Continental's PETS flights were all booked full for at least six months past the date we intended to travel, so even though we lived in Houston, we were unable to use our local airport and airline.
We found a good solution though, and one that worked out to be (marginally) cheaper than flying Continental. I freed up about two hours worth of time and called American Airlines, which flies the PETS Scheme out of Dallas. I told them what my situation was, and we ended up flying from Houston to Dallas, where the cats were set up on an official PETS flight from American Airlines Cargo. It worked out beautifully.
I imagine you could do the same thing, check the DEFRA list and fly from where you are to the nearest city that flies on the PETS Scheme.
A tip, if you don't mind me offering it: Book your flight to land in Gatwick during the BRITISH working day (Monday-Friday). If you arrive between 9.30am and 5.00pm, you will pay the minimum fees (which are still pretty steep). If you arrive outside those hours or, God help you, on a weekend day, the fees will increase 30%-100%! Also, be prepared to take a taxi from the airport to the cargo area (about £10 each way) and back to the airport. And you will probably have to wait on your pets for about two hours as well... I had to pay about £200 at the airport.
It wasn't a good scene, I was awfully cranky at the airport, and waiting for two hours was no picnic. I had to leave my wife with the luggage at the terminal while I took a cab out to pick up the cats -- my poor little lady thought I was dead! Our mobiles couldn't pick up a signal and there was no way for me to tell her, 'Hey, I'm alive, and sitting here staring at a water-cooler. They say that soon they'll give me the cats!'
Best of luck to you -- I know that in our case, all the trouble was worth it and the cats continue to give us the joy they've always given us. Because I lived in the flat for two months before bringing them over, my scent was everywhere and they relaxed and felt at home as soon as we got them in the door. Maybe after 24 hours in a cage, they would have been glad to see anything! And it does seem as though American Airlines treated them very well.
Do let us know how it works out -- nothing better than a happy ending to a PETS Scheme Story!!