The currency always depends on the website domain (.co.uk, .it, .ch, etc) through which you place the order and the invoice will display the same currency: if you are browsing the italian website you will see prices in €, on the Swiss site in CHF, on the English one in £ and so on. The invoice currency will therefore be the same of the online quote.
N.B.: on the co.uk website the currency is in £, on the .com site it is in €.
If you ship your order abroad, please note that the invoice will be issued in the same currency of the website, it won't vary according to the destination. If, for instance, you ship and invoice an order to the UK from the .it website, the invoice will still be issued in €.
Read here how to ship abroad.
If you still have any doubts, don't hesitate to contact us : we'll be happy to help you!