A credit score is one of the main things a lender looks at when they’re making a decision about lending to you. In a nutshell, your credit score will help decide if you get access to credit, and the cost of that credit.
All the main UK Credit Reference Agencies (CRAs) have a different scoring profile and different lenders will use one or more of these CRAs when making a decision. Typically, the better your credit score the more likely you are to be offered finance and the more likely you are to be offered better interest rates.