Through a glass, darkly by Jostein Gaarder
Published by Phoenix

A moving story of a young girl dying from a terminal illness.   Cecilia is visited by the angel Ariel and through conversations with him, she slowly comes to terms with dying.

Although this sounds like this book would be really depressing to read, it isn't.   It's quite uplifting to read as you join Cecilia on her journey of sorting out her feelings of anger and despair to hope and grief to finally calmly accepting her situation and being thankful for her family, friends and her life.