I don't know about the british insurances, however my insurance included a 'Engine and drivetrain'-clause. So my gearbox trouble was covered by this. It was only valid for cars less than 8 years old and with less than 100000 km on the road. But you probably checked this already...
Cheers 0100100. I havnt checked this with my insurance but would be extremely surprised if this were the case. I'll check tomorrow tho. cheers.