this didn't work on £93 order, but the 2 year old AD1 code gave me £4.50 ish off! (also got £15 off on the current automatic 6 for 5 deal so final price was £73.
Depends on what you are buying. The coal I purchase comes in at 28p/kg when I purchase 300kg (12x 25 KG bags). The 10kg bags you get on a garage forecourt are never good value I find.
The coal is much cheaper per kilo in asda, and is also sold through their online groceries site, with delivery from £1 to your home or free click and collect. Hope that helps.