I have visited the Beanshacks market stall in Blackbushe, Windsor and tasted their coffee. It is trully heavenly.
Since then I place regular orders on their web site
http://www.thebeanshack.co.uk. As I live in the Essex area I also get the benefit of free local delivery, which means they deliver to your door in person. Othewise you have to pay for Royal Mail first class delivery, which I would pay as I think it is worth it.