Yes, I'd forgotten that small detail, the UK has zero COVD restrictions now. In which case just try creating a Salesforce upload for UK to Italy via
https://digitalboarding.force.com/BA...ionEmbarque_BA
[more details in the Document Upload thread]
and upload - in one step - both your vaccine certificate and the Euro PLF. Either merge these two items into one photo, one upload, or select 2 files in the box.