THIS HAPPENED IN ENGLAND

I am a new driver, only passed 2 months ago, and I was at a store car park, in a hurry and without paying attention I think I touched someone's car... I panicked, backed up, and got in the parking space next to them. I ran in the store trying to get the Customer Service Desk to shout out their license number so I could meet them, but, there was a long que, and I thought by the time I walked to the store and back, they would be there already, and I returned, when I got back to my car and theirs, the car wasn't there anymore. I inspected their car, but it looked like it did not have any damage, hopefully. I feel really bad, and I am not sure what to do. Would this be considered a hit and run from my side? I am really scared as I am still a new driver, and at the same time I feel extremely guilty about it, but, from the looks of it, what could I do?