Hi Max, I'm sorry to hear that.
Have you ever had any credit cards or loans? If not its quite possible you don't have a credit rating, I don't believe you can get a rating unless you have credit.
You can also check your credit rating free of charge, take a look on Money Saving Expert website, there are guides on there.
Speak to your new landlord, he may take a bigger security deposit or you could offer to pay the rent X months in advance if you can afford to do this. A colleagues father was recently refused a flat because he failed the credit check, he simply offered to pay a year's rent in advance and he's now the happy occupant of the flat.
Hope that helps.
