>> I listened to a few of Loreena McKennitt's songs, and I like them a lot. She has a wonderful voice and I really appreciate the mystic storytelling quality of her songs.<<

Yay!

>> I haven't really checked out any filk yet, because I haven't had time, but that is on my list of things to do. <<

You may find it helpful to look up Pegasus Award winners.

These are some filk genres with examples.

Ranker lists some of the best filk artists and bands.

>> Asking a librarian or a music store owner are things I never thought about doing but are always good suggestions. <<

Asking an expert is usually a good way to find things. Asking a librarian is a good fallback if you can't find a topical expert. Any specialty store should have staff who can recommend things suited to your needs. A general store may or may not have knowledgable staff.