Isn't the internet great? When I was a student 20 years ago the internet was basically user-groups. Now, with everything else, the most useful bits are sometimes forums and yahoo! groups. I've just been told that my aluminium will flow better with 5%-6% copper added to make an alloy. That's just saved me a lot of experimentation and googling so thanks guys!
Also I've now found that bioregional charcoal has moved to Sainsbury's from B&Q. It's twice the cost but it says that it supports coppicing and local charcoal production. I'll do some quick googling to check it's all true, but I expect that's the direction I'm going in. Either that or scrounge some wood and start a fire for charcoal. I've done it before, so I know how to do it. It's just another stage that I hoped to bypass this time!
So off to Freecycle to keep an eye out for any copper scrap and firewood. Plus an old wheelbarrow for making a charcoal clamp. I'm also asking around to see if I know any plumbers who could collect pipe offcuts for me. I do have some pipe in the garage that I could use if need be.
Thanks for comments and followers!