How does discovery work and do I have to hand over all my documents?

Yes, in civil proceedings you have a duty of disclosure under the High Court Rules 2016. You must disclose relevant documents, including those that harm your own case, that are or have been in your control, and you must take reasonable steps to preserve them from the time you contemplate litigation. Deliberately withholding or destroying documents can lead to serious penalties. You can withhold documents protected by privilege, most commonly legal professional privilege for confidential communications with your lawyer for legal advice, and litigation privilege for documents created for the dominant purpose of the litigation. Settlement negotiations may also be privileged. Your lawyer will help you review documents, decide what is privileged and prepare a list of documents that satisfies the rules.