from landrover forum it appears that either cutting a groove and using a screwdriver or spot welding a nut on are the best options, the bolts need to be removed whilst warm as they use a lot of threadlock as well.
Found a Land Rover specialist who can remove the bolts for us. It was looking like a load of hassle. Land Rover fora all said its a PITA and either needs welding a nut on or angle grinding a slot but there is carpet which may go up in flames. Best to get a professional to do the work.
from landrover forum it appears that either cutting a groove and using a screwdriver or spot welding a nut on are the best options, the bolts need to be removed whilst warm as they use a lot of threadlock as well.