Steve
You have said that you are going to court. This infers that you have a date. In this case you would know the builders defence.
But you stated that the builder has failed to respond.
For those who do not know, in a civil case the claimant and the plaintiff ( the builder) submit their submissions in writing before a
court date is set.
If the plaintiff does not respond it will be a forgone conclusion, and no witnesses will be required.