STOP PRESS! VERY EXCITED!! OK, I'll stop shouting now. But we've just had an offer from a Somerset haulage company with national networks that could possible solve all our issues. They are going to try to get a network of palletline depots to receive and pass on our plants nationwide. Or possibly arrange to have their trucks meet us to pick up plants from us at motorway services.
Obviously we'd now need to get our gardening heads together to think about how well our baby plants will travel - these won't be vehicles specially adapted for plants, so at the very least we'd need to give them a good watering, maybe prune back any trailing bits, tuck them up nicely....etc etc. But this sounds really, really hopeful!
Gardenjeannie, your plants might be on their way soon!