If your credit score is poor then there are steps you can take to address it. Registering on the electoral roll can help, as can cancelling unused credit cards. If your score really is poor then you should make an effort to make any repayments on time and to settle bills – this shows you’re a sensible borrower.
Clearing debt can also make a big difference but if you’re using savings to do so then make sure you leave some emergency money in an easy access account. There are more useful tips available via the Money Advice Service.