I would offer to drive your cats down to Soton but my first available weekend is 30th September.

I reckon I could do it in around 10 hours. There's a spray you can buy from vets which is filled with some kind of pheromone that cats give off when they very happy and calm. On the advice of our vet , we sprayed their carry baskets with it when we drove our cats from Cambridge to Edinburgh and, after an hour of 'crying', they settled down and were fine for the rest of the trip.