Hey Simon,
PPL don’t collect these kinds of Neighboring Rights on library music. If that’s the bulk of where your productivity lies (as opposed to writing songs) I’d recommend joining an agency dedicated to collecting these rights for library music composers. NRG and Rident are two of the big ones to look into. There’s a lot of paperwork to sign at the beginning, and often have a payout threshold. but they are pretty transparent
in their accounting. As you’d expect they take a percentage of what they collect. Hope this helps, and good luck!