Hi, welcome to the site. Maintaining confidentially with paper-based documents involves how you ensure they're stored and kept safely - for a period of time that reflects their lawful requirements, not seen by anyone without the permission to do so, not removed from the premises unless the individual has the authority to do so. Times where information is shared confidentially - in privacy/place that's private so that what's discussed and shown is not accidentally overheard or seen.
There is an
example reflective account on this thread if it helps
Page 4 of the
level 5 handbook on amazon.co.uk looks at professional responsibilities towards the
Data protection act
Best wishes