Hi Riccardo Ib,
As per the guidance below the supplier cannot treat a supply of goods as an indirect export if they are purchased by a UK resident or visitor for their personal (non-commercial) use:
VAT on goods exported from the UK (VAT Notice 703)
If the goods are sent by the supplier to a destination outside the UK, however and the supplier is responsible either for arranging the transport yourself or appointing a freight agent then they should charge you at the zero rate as a direct export.
If you are classed as a diplomat then a supplier can zero rate the supply to you if the goods are delivered to the FCDO or FCDOS (formerly the FCO, FCOS and Department for International Development) for export through diplomatic channels within 3 months of the time of supply.
Thank you.