In case anyone is still out there, 2 years after the conversation seems to have ended, I can report that Dutton will not be issuing Volume 2 of the Ashton sonatas, even though the master with the other 4 sonatas has been ready to go for a long time. They have changed their focus, and it doesn't include solo piano, British or otherwise, at least at the moment. You might find the album released within the next year or two on another label though.
I cannot speak for Toccata's plans re Ashton.
I cannot speak for Toccata's plans re Ashton.