Right so this is the kind of thing that just builds and builds on you isn't it. Weeks of hearing something and your brain just starts filling in the gaps with whatever it fears most.
Curious what the footage showed. Was it a clean recording or did you get anything weird like static or gaps in the timeline you couldn't explain? I ask because a mate of mine in Manchester had something similar - turns out it was squirrels, completely mundane explanation. But he also had a stretch of about 40 minutes on his camera that just... didn't record. Camera was on, timestamps kept going, nothing captured. That bit I still think about.
Attics are strange spaces in general. Liminal in a way that's hard to put into words. I've had my own odd experiences in enclosed spaces like that and theres something about the way sound behaves up there that can really mess with you.
Post the footage if you can. Even if its nothing dramatic people here will give it a proper look rather than just dismissing it.