The student loan is an unsecured loan. You do not have to provide an asset (e.g. a house or a car) as security that can be seized if you don’t make payments.
How much you repay depends on your income rather than a pre-set repayment rate.
Inland Revenue deducts repayments directly from your wages.
Any interest is calculated in such a way as to ensure that no borrower's loan balance ever grows by more than the rate of inflation. Visit the Inland Revenue Student Loan website to find out more about how interest is calculated.