Reddit reviews Austin Osman Spare: The Occult Life of London's Legendary Artist

For a biography I suggest This one

you can find works here
and some more here.

If you like Liber Null I suggest picking up Frater U.'.D.'.'s book on sigils. Which can also be found here

Austin Spare, often called the greatest magician who ever lived, supposedly could do anything he wanted, but ultimately didn't want much of anything. Even he said something to this effect when asked why he was such a great artist but peaked in his teens and languished in poverty and obscurity forever after. His answer was pretty much "perhaps this is what I want." The new biography forwarded by Alan Moore is definitely a good read.

There is a good biography Austin Osman Spare: The Occult Life of London's Legendary Artist by Phil Baker. I thought the most notable thing about him was that he seemed fascinated with his own imagination. Artists with exceptional access to the psyche run a great risk of becoming entranced by their own soul. It is possible to gain the creative powers of the dreaming mind but turning that into art isn't easy because you are trying to make use of a ability beyond conscious invention.