Welcome to the Roku Community, @IrishFyre!
Thanks for reaching out about the availability of the content This Is Spinal Tap. We'd love to help you access this directly from your TV.
Firstly, kindly ensure you've searched it outside The Roku Channel and directly on the Search option on your Home screen. We've also checked and this movie is available via Pluto TV and Add Creative Veinz apps.
You may check this website if you want to look for available content on the Roku streaming platform: This Is Spinal Tap | What's On | Roku
We hope you find this information helpful.
Best regards,
Carly
Carly Y.
Roku Community Moderator