What would happend if...? Past CCTV footage?

I recently got caught trying to steal 2 packets of sweets. As I was leaving, the shopkeeper stopped me, I handed back what I had taken, she told me she had seen me doing it before and she had caught it on camera. The she asked for name and year (cos I was in my school uniform). I gave a false name but real year and left. Is there anyway that past CCTV evidence could be used even if it happened a couple of days ago? What could my possible punishments be?