My partner and I have recently got into charcoal production. The Artists Charcoal that we produce is made on the fire at home from bits of willow leftover from basketmaking.
It is an interesting process where the wood has to be burnt but the amount of oxygen it has access to is reduced. This burns off all the impurities in the wood leaving pure charcoal. We seal it in a tin and then put it on the fire.
We now have boxes of this charcoal for sale in Neames, the Art shop in Rye and Artwright in Hythe
You can also get it on ebay here
We make it at home on a fire so it might not be up to the professional standard of some of the big suppliers so if you are an artist that requires all the pieces in a box to be a standard colour and softness it may not be for you. We have met artists that enjoy the variation however and of course our charcoal is cheaper