It really depends on the terms and conditions of the loan. We're all frankly guessing to if there is a saving to be had or not based on previous experiences of different financial services but when I had a loan with Zopa, it was compound interest calculated applied month so each month, the interest calculated for the month got paid off first and the remaining payment deducted from the loan balance. The more I paid each month, the less interest was accrued each period.
If it's a fixed rate on a fixed term, then no but who knows. Give them a call like others have suggested
Good luck