Hi all, just read the bit about checking glow plugs and thought I would add this warning. Couple of years back I had a Hyundai i30 which got hard to start in cold weather, suspecting faulty glow plugs I took it to my local garage to get them changed. After changing the plugs the engine rattled, you got it, the tip had snapped off one of the old plugs and was rattling about in the cylinder, resulting in a scrap engine.
Fortunately there are decent honest garages around and they accepted the mistake and fitted a replacement engine at no cost to me, I gather heater plug tips do occasionally snap off on removal so check properly before starting the engine again.