(Found) Help: Female Brit author; circa 2004; out of body travel

[FiGi]

Hi, Years ago I read a book in which a young boy discovers a way to go to another galaxy while remaining physically in his attic. Setting: rural England, small village. In the other galaxy, the inhabitants wore breathing masks. The boy could see and hear what was going on but couldn't be seen. He would go and come back. Back on earth, his relative who had died had magical powers of some sort. I'm not completely sure of the above details. The book ended in the middle of the story. Any one know?? Thanks so much! Annette

 

[HareBrain]

Yay, I know one!

Amanda Hemingway: The Greenstone Grail. It was the first of a trilogy.

 

[FiGi]

Thank you!! I think that is it! You are the best.