Possible Clues:

• Fantasy and reverie for the flute?
• Fanciful plan
• Futile hope to find a character in Dickens edition with 500 pages
• Churchwarden, perhaps, acquires ideal castle in Spain
• Wishful thinking of smoke there while asleep
• It's quite unreal to have sheets coming through the tube, it seems
• Revolutionary aim appeared, after leaders left, an impossible plan
• Out-of-reach goal
• Put sweet lines down on paper, a fantasy
• Reverie for flautist? Vain hope!