Pete, try raised beds for the figs, that should help with some of the problems with the clay, not to mention a big load of manure and gravel. I have seen in Pon's book and Baud's book when planting a fig tree they put around 4-6 inches of gravel, then good soil and manure on top if I understood it right, if you are able to do the same (I know it's a lot of work) then you should be doing not too bad that way.
If you need to get rid of light types, Martin would be able to help you out I think, the barrel seems well used.