help figuring out solo:"Oh! Sweet Nuthin" Velvet U

This is a basic three chord song: C Bb F, over and over and over. Yet somehow beautiful. I'm trying to tab it out (my first attempt at transcribing). I figure that the song is in the key of F ? since Bb and C are the 4th and 5th of F, respectively. But it sounds to me like one of the main notes in the solos is C on 3rd string, 5th fret. And I've found some other "good" notes around the 3rd position of the 3 high strings.

Can anyone out there confirm if I am in the right key, and the right position, etc? Even better, if you could suggest a scale he might be using, it would narrow my search!

Thanks in advance 8)