I read a book that my mom gave me in High School for a book report. She cannot remember the name of it. I can only remember vague bits and pieces. I remembered that it was a bit creepy. It involved spirits and demons and it was based somewhere in England. I feel like it was Scottland or Ireland. I remember the main character being alone and possible on a quest. I know it's not a lot to go on but I had to try!

Sounds like the classic English class Boewulf (might have spelled that wrong).

Moon by James herbert??