A gift card is the honest answer when you do not know what somebody wears. It carries an amount rather than a fragrance, and the person receiving it chooses.
The code is spent at the checkout, in the field marked for a coupon. A card worth more than the order leaves the rest on the card, so it can be used again. It is not tied to a name or an address.
It is bought on its own, in an order of its own. That is deliberate: it keeps the card away from shipping and from the free samples that come with a bottle.
There is no VAT on the card itself. VAT is paid on whatever it is spent on, in the order where it is spent, exactly as if the person had paid by card.