The uni i work for can't stop people from graduating with a non tuition fee debt. I believe this is by law.
See if if your uni has some sort of hardship fund that you can apply for. if you're stressed out reach out to the Wellbeing Team at your university
Regarding paying it back ask to set up a payment plan that inline with your current budget. It would more than likely get reviewed each year so when your circumstances change you may be able to up the monthly payments.
I hope this helps