I agree with everyone else not to pay off a 0% loan early.
Also, something to bear in mind: in the UK we pay our student loans back directly from our pay (as it sounds like you do). My husband asked why I don't include his loan in our net worth (as a negative amount). The answer is this: He only repays it if he is working, and if he earns over a certain amount. So I see it as more of a tax. In the event that he doesn't have a job for any reason, no payment will be due. I don't count other future tax liabilities against our net worth, so I don't count this either.
I don't know if your loans are also only repayable if you are in work, but if that is the case, I would caution against paying it off early, just in case you are ever unable to work for any reason.