Articles on Avweb indicate that it's not altogether uncommon for pilots in the US to land on roads in emergencies, and one recently managed to land perfectly on top of a huge truck which was going his way (took him a while to figure out why his ASI still showed 50 knots after he'd completed a smooth dead-sticker, whilst the truckie wondered why his rig suddenly felt so draggy and gutless), but finding a stretch of straight road without traffic in most parts of the UK would, as noted above, be a pretty tall order.