Use a concise facts sheet, a record index, a current programme reference and a list of unanswered questions with responsible people.
Keep the file actionable
For every missing item, record why it matters and who can obtain it. Avoid collecting sensitive documents without a defined purpose. Counsel should identify the actual filing evidence under current instructions if the decision is to proceed; a readiness file is an aid to that decision, not a substitute application.
Collect in stages rather than all at once. The first stage is short: identity and citizenship documents, a plain chronology of residence and travel, and a written statement of who would fund the gift. That much supports an initial assessment without exposing sensitive material to no purpose.
The second stage follows that assessment and is defined by it, covering financial records, corporate authorisations or civil documents according to what the classification and current instructions actually require. Certification, translation and legalisation belong in a third stage, once the list is settled, because those steps are the expensive ones and they are wasted on documents later dropped. Hypothetical example: An agricultural drone services founder has an entire corporate minute book legalised early, then learns that a single resolution would have answered the only question anyone had.
Maintain a running list of what is missing, who holds it and what each item is meant to establish.