Hi Keith,
You would only need evidence of export of goods if the goods were leaving the UK as that would justify an export from the UK.
If the goods never enter the UK then no evidence is required.
The place of supply rules for goods are determined by where the goods are when they are supplied so if the goods are not in the UK when supplied then the
Place of Supply will never be the UK.
Please see below:
VATPOSG2100 - Background: place of supply and its impact on the scope of VAT
Thank you