FWIW, my personal take on this if I understand the FAA/CAA ruling correctly is that yes you can give them to the garden centre and they can do whatever they wish with them, commercial or not. The FAA/CAA would only be interested if YOU received payment for the pictures. As you haven't/didn't I don't see a problem. I assume you flew as a hobbyist i.e it was originally a personal pleasure flight. No problem.
No - your understanding is incorrect. It's not whether you received payment, it's whether the intent of the flight was recreational. If it was, at the time, then subsequently you can do what you like with the material, including selling it. What you can't do without a Part 107 is fly for any purpose other than recreational.