You will need to be a homeowner to get a unsecured loan of £15,000 !! Even though they offer loans unsecured it's very rare they will lend £15,000 unless you have a property (it's just their criteria), even though the loan wont be secured on it.....
Most personal loans they offer will be up to £5k max as it's all about risk to them .. Since the credit crunch banks are even more strict than they use to be..
You would probably need to use a sub prime lender like 'black horse' but again 15k is a lot of money for an unsecured loan ..
http://www.loans2compare.com