Below are some links to the BRC website so you can train to be an auditor in the packaging industry.

https://www.brcglobalstandards.com/training/

TO train as an ISO auditor you would normally be part of an ISO auditing organisation.

You can be trained to be an ISO auditor at any of these organisations check they are approved on the ISO website

https://www.bsigroup.com/en-GB/iso-9001-quality-management/iso-9001-training-courses/qms-auditor-lead-auditor-iso-9001/

You can be certified as a BSI auditor - please see link below;

https://www.bsigroup.com/en-GB/our-services/training-courses/auditing-courses/certified-auditor/