Hi Leon,
Taking photographs of a late afternoon sky while trying to achieve details in a shaded foreground is not easy. It does take the effort in post-production to make both the sky and the foreground look convincing.
In all, I think you have made a reasonable job of what you have here. Perhaps the could only adjustments I would make would be to adjust the midtone contrast in the foreground.
The simplest way to do this would be to open up the Shadows/Highlights adjustment in Photoshop and click on the Show More Options box. Down the bottom you will find the slider marked Midtone Contrast; slide this across to the right by about 30 or 40% and I think you will find the foreground looks a little more real.
Cheers, Anthony