Have you got an SD card in the drone? All your photos will be on there, and high quality videos too. The videos on your phone are lower quality, recorded from the live video stream as you're flying. Photos don't automatically transfer, but can be transferred via the album part of the app when the drone is on, and the phone hooked up to the controller. Alternatively use a card reader.
I don't want to lecture how and where you should fly your Mini, but for your own sake read up on the UK's drone laws/drone code. A good site is this, with simple diagrams to explain:
dronesafe.uk