I'm not sure. The interest on the loans is so high now it's insane - 6%, and no bank is gonna give 6% interest. I could dump it in stocks, like Berkshire Hathaway, but I could end up being f*cked by the stock market.
But, student loans aren't really a loan. They get wiped aged 50, and there is only a fixed amount relative to earnings to pay. If I had a >£60,000 job i would probably pay it off, but under £40k I would invest.