Hey Tattyjacket,
It appears that you're having a problem with attachments you're adding to an email. The receivers can't open them, and we're glad to provide assistance.
Add attachments to emails in Mail on Mac - Apple Support -- If you're using the Mail app on your Mac, review the steps in this article to be sure you're attaching them correctly.
If either file is being stored in iCloud previous to sending, they would need to be physically located on your Mac first. This would also apply to any photos you may be syncing with iCloud. If "Optimize Mac Storage" is turned on in Photos > Preferences > iCloud, you'll need to tap the photo you'd like to send first to have it physically downloaded to your Mac.
Please let us know the results when you're able.
All the best.