Postgraduate degrees do not use the First, 2.1, 2.2, third classification.
My marking scheme for Masters level is similar to Sneaks':
Pass 50 to 65%
Merit 65 to 70%
Distinction over 70%
So you have a pass...and not a 2.1 or 2.2.
However, if your degree is from outside the UK, a 57% will not necessarily equate to 57% in the UK. You will need to have you qualifications officially converted.