Normally, unsecured loans are only offered to people who have a good credit profile or a track record of paying back loans in a timely fashion. An unsecured loan is not tied to any sort of asset - for example, a secured loan is tied against your home and provides the lender with "insurance" if you don't repay the loan, so they're often more willing to lend to people with bad credit as there is less chance of the customer defaulting with one of their assets secured against the finance.
When judging an application for a loan lenders will access credit reports from credit references agencies and judge the "risk" of the customer; a high risk customer is someone who has defaulted in the past or has county court judgements, whereas a low risk lender will have a good record of loan repayments. The amount of loans you've applied for in the last 6 months will also affect your credit rating; if you've applied for more than 5 loans in 6 months (and been rejected) you may find it difficult to obtain a loan, even with a fairly good credit profile.
Unsecured loans for a fair credit rating will normally have a higher APR than other loans. This is, again, a form of insurance for the lender. By offering a high APR you're likely to repay much of the loan amount early in the event you default in the future, so the company won't lose as much money if they offered a competitive APR rate.
Unsecured Loans for a Fair Credit Rating Lenders
You might not be able to find a bank loan or high street loan for fair credit. However, payday loans such as Wonga and LendingStream may be willing to offer a loan to you if you don't have perfect credit, but these won't offer long term repayments.
Aspire Money (aspiremoney.co.uk) do offer long term unsecured loans for people with a fair credit rating but their APR is around 53.9%.
Provident Loans providentfinance.co.uk) and Greenwood Finance (greenwoodfinance.co.uk) also offer unsecured loans but their APR is a massive 272%. Their loans are also considered "doorstep loans" and certainly won't be a flexible finance option.
FML Loans (flmloans.co.uk) offer guarantor unsecured loans for people with a fair credit rating, or people with a bad credit rating, as long as they have a guarantor to support their application. Again, the APR of the loan will be around 52%, which will result in high monthly repayments.