Hi Stephen,
Very nice work so far. I like how the soft wavy terrain builds up the depth, good pov for that. The grasses look good to me, nice color-variations! What is it what you don't like about it? The terrain/surface could use some more elements or variation like patches of grey fake stones and maybe some water somewhere.
I see what you mean about the clouds but I think the shape and scale of the clouds are fantastic and fit the scene very well. Just like Mr. Lamppost said you'll have to sort out how to make the clouds look softer and how to get the lighting sorted out to get rid of the dark-grey shadows. I think 'PG' knows quite some about this.
Looking forward to see your update, hope you'll stick to your clouds a bit
Martin