As there is a recruitment crisis in teaching atm it's an incentive to get high achieving graduates to train as Computing teachers.
As for how much student debt I have, if you really must know, I currently have 43k in student debt, my PGCE next year increases that by 15k. I'm doing a masters straight after, so another 10k. Then I'm possibly going to do a second degree (2nd degrees are now funded for STEM subjects) at the same time as my PHD, so possibly another 50k, so around 118k in total by the end of my academic journey.
Don't worry though, my PHD is fully funded, so you don't have to worry about that being added to my debt - you're paying for that out the goodness of your heart.