Hi there @nickjimward and welcome to the community! If your preferred artist isn't available, this may be to do licensing or legal constraints in your country between the artist or their label and Spotify. Sometimes, we are unable to get music from an artist because there are some contract type questions.
if there's someone you'd like to hear, but can't see on Spotify, I recommend reaching out to the record company to see if they can get the music added. I can assure you that Spotify wants EVERY artist and EVERY song available for its customers!