I was covered by the AA but never had to use them, thank gawd. Think it cost around 80 quid per year on top of my normal aa car cover. Believe RAC do similar cover. Normally depends on the vehicle towing - is that covered by any breakdown companies?
Most insurance companies will offer breakdown cover too.
Well I guess you neednt have car cover to use ESS. They come and either recover trailer if car broken down or if trailer problem they send transport to rescue horse. But obviously car will be pretty stranded!!
I specifically changed mine, so that the truck was covered with the AA and enabling me to take out cover with these guys http://www.horsebox-rescue.co.uk/