I have just found a flat to rent, and didn't have to pay a fee, but that's because they are not doing a credit check. They simply needed a guarantor instead (home owner who can guarantee the rent). I gave a deposit equivalent to one month rent on the day I said I was taking it, to make sure they kept it for me and didn't do any more visits. I will then pay a month rent on the day I sign the lease, which will also be my moving in day.
Another agency I went to required a �30 credit check fee/ application fee.