Sparkplug,
A couple of things for you, if its just for bbqs then there are uk producers which sell to garden centers. I know of one for B&Q, which is sett up by an organisation who specialise in getting small (but still significant amounts) producers in contact with the center (i also saw some in ASDA), i am told by someone that uses them that its very good. These are clearly marked and actually not that much more expensive - they usually light far better and burn very well (the conditions in the uk are some of the best in the world for growing timber to charcoal).
I read about what was said about co-operatives above but know that this isnt always the case, they system i know of is sett up with a regional agreement where they supply only their 'local' store. Brilliant for people who do a lot of wood managmnet and thinning, i have no idea why more wildlife trusts etc dont do it (much easier than transporting firewood).
Im actually in cambs and have done a burn earlier this year in the garden (only use a little oil drum method)- I find that if you do it earlier in the year when people dont have there washing out its fine although i have now run out of home made, and next year will be doing several in early spring.
As an aside (and im probably preaching to the converted here) as mentioned above imported charcoal often comes from slash and burn destroying good habitat and even salable wood, accidents are frequent and conditions not appealing. Not to mention methods are usually very wastefull.
If you look on a bag of briquetes you will find that a large amount is 'filler' or 'binder' this is often cement dust, not only does it mean that what your food is cooked on but it explains why we need firelighters. U dont for uk charcoal. (another gripe of mine, we wouldnt cook on noxiouse chemicals but we will put them on coals then put the food ontop of that...)
Hope that helps