This is not easy in Britain, to do productively, unless you live in the warmer south east.
Your soil sounds fine for growing everything, and the fruit cage is worthwhile as birds love them, although a sufficient quantity might be more than most flocks of garden birds could eat… I have not tried growing them to eat though and wonder how you will get on with hulling all that seed? It might be more productive to use your precious soil for other food crops (dried beans such as runner bean Czar), also naked pumpkin seeds – but I am unsure which variety is best, of those currently available.