Before anyone starts civil proceedings in court they should follow one of a series of pre-action protocols which is suitable for the type of case. That's unless there is very good reason not to do so (for example, time is running out for suing and its too late to do what the protocol says). They are meant to write to the other side and explain what their claim is about and give them the opportunity ro respond and provide copies of relevant documents on which they would rely if the case went to court.
Failure to comply with the appropriate protocol could lead to the court halting the case for a while or denying the defaulting party their costs even if they win. That's what has just happened in the county court at Bolton in a claim which was brought against Tameside Hospital NHS Foundation Trust. The claimant did what was required according to the protocol she had to follow and the hospital trust responded by denying liability but going on to say they didn't have any documents to show the claimant. In fact, they did have relevant documents and the claimant did not get to see them until after she had started her case. Had she seen them earlier she would probably not have sued. When she did see them, she abandoned the case.
Abandoning a case usually means that you pay the other side's costs. However, because the hospital trust had failed to show the claimant the documents which the protocol required them to do, it was ordered to pay the claimant's costs and bear their own.
You will find the protocols a www.justice.gov.uk. protocol In the pipeline is a new protocol for claims for debt by a business against an individual (including a sole trader).