I recently got a £15K loan through HSBC at 4.9% to complete my MEIR. I earn an average salary and neither of my parents own a home to secure it to.
The key thing is to sensibly build your credit score - you can't get a good score until you 'borrow' money and then re-pay. The quickest way? Apply for a credit card through your bank. Start off with a £500 credit limit, put your shopping and your petrol through on it, pay it off in full at the end of the month and repeat.
The quicker you have a decent credit score the easier everything becomes, I'd say it's pretty essential in this day and age in order to not get ripped-off with loans, mortgages etc.
P.S. If you try one credit card application and get rejected, do not go around trying others for at least a week. Each application will make a mark on your credit score, if you make too many attempts in a short space of time then it doesn't look good.