I only need one, so I'd rather not buy a load of plastic that'll make a messy cupboard even messier. I'm sure there are better solutions than a ziplock bag, but as long as the parcel will not be refused for it not being an ISO approved pouch it's good enough.
I think you need 'adhesive document pouches'
e.g. https://www.staples.co.uk/document-enclosed-wallets/cbc/1414.html
https://www.kitepackaging.co.uk/scp/sealing-and-security/document-enclosed-wallets/?gclid=CjwKCAiAl4WABhAJEiwATUnEFw2jDHsYV4Nz-87tRbyl8zE3Gl0hZQJM3tCN_ctHCDutTciMophCGxoCQYoQAvD_BwE