Hi Georgia V,
If you sell goods at a trade show then the Place of supply would be where the goods are when sold and so the Place of Supply would be in France.
However, if you are providing services then the Place of Supply would be where the business customer belongs and if the business customer is overseas then these would be subject to the reverse charge procedure by the business customer.
Please see the guidance below:
6. The place of supply rules for services
Thank you.