I've bit the bullet and bought/installed a diesel heater. I've held off up to now. I would normally just put on extra clothing and work a little harder to keep warm but my medication is making it almost impossible for me to work in a temperature below 9C (temporarily, I hope to be off it by end of February). I also had nowhere to put it inside. But, I watched a chap install his outside which, although not ideal, was an option I could work with. This means I won't be able to re-circulate warmed air already in the workshop but will have to continuously heat fresh air from outside. Diesel price local to me is around £1.69 so it still seems to be the cheaper fuel. Red diesel would be cheaper but I would have to buy it in bulk. Any hints or tips from longer term users?