I'm (perhaps) an 'early intermediate' pianist. Are there any Vaughan Williams pieces I could look at that I have a reasonable chance of being able to play? Wikipedia suggests that I may be out of luck due to a complete absence of solo piano, but I'm not inclined to assume that it's 100% correct.
You might also want to have a look at some of his songs for voice and piano. In many of them, the piano accompaniment is not too difficult, and the piano doubles the voice, so it's "complete" as a "Song Without Words." (For example, his Three Poems by Whitman aren't too complex.)