A lot of court paperwork confuses people as they are unfamiliar with it, and in the case of a CCJ stressed about its effect. So here is how to complete it. The form used is called a N244 and there is an online version for you to use here.
As well as the form and the £255 fee, you should also attach an explanation of why the monies are not payable and evidence of your having moved or being unable to respond to a claim.
You will get a reply from the court with a date for you to visit a judge, have a 15 minute chat about why you couldn't respond and why you have the chance to defend at any new hearing the claimant may want to request. [Often the parkign company don't want a new hearing to avoid having to pay yoour £255 back]
Once the set aside has been granted, the courts will advise the credit agencies and the CCJ disappears from your file.