Picked up some Newflame smokeless coal on offer at £4 for 10kg.
Slower to get going than the wood but once it's up and running, half a bag lasted most of the day and into mid evening, with the odd poke to keep the air going under it.
Sure is better than some smokeless coal I tried last winter, which was atrocious as I just couldn't get it up to a decent temperature.
Thought I must be using it wrong ( lighting and vent controls etc.) but this new stuff is so much better with the same controls.
Got my stack of wood so may alternate and use that if I just want a quick blast for a few hours.
Not one for working out exact costs comparing to wood etc. but it doesn't appear to bad on the wallet.