Any kind of business that you have a financial relationship with: a bank, a mortgage company, a credit card issuer, or even a letting agent is very likely to use your credit report to assess your creditworthiness before accepting your application. They will be looking to see that you have a history of making the payments required of you in full and on time.
Evidence of the type of events like defaults and CCJs raise red flags to lenders, as they indicate that you are, or have been, experiencing financial difficulty, or will not pay them what you’re due to for another reason. This means you may find it difficult to borrow money, which might hinder you if you need to use credit for a financial emergency or for a planned purchase.
If there’s a good reason for your having a negative marker like a late or missed payment marker on your report, such as if you were unwell and unable to work, or lost your job, you can file a notice of correction on your credit report, which is a 200 word statement that allows you to explain your circumstances. This will then be visible to other lenders who view your credit report so that they can take it into account when deciding whether to approve your application or not.
Over time, the impact bad credit markers have on your ability to get credit will lessen.  Whilst you wait, you can become more knowledgeable about rebuilding your credit rating for the future, should you ever need to use credit, either for a short-term loan or for a longer-term borrowing need.
Whatever your reason for having bad credit, it’s important to seek free, impartial advice from a not-for-profit debt advice agency if you’re finding it difficult to manage your finances, and find a way to clear what you owe to get back on track. The Money Helper, StepChange and National Debtline are three not-for-profit services that are here to help.