Hi Waves,
What I was suggesting was that considering you have nothing to lose, that you choose UK in the dropdown menu when registering & using a Belfast postcode, & your ROI address in the address box. The chances are that your item could find it's way to you from Belfast. There is no guarantee that it would, but if it's a case that you would otherwise be throwing the voucher away it's certainly worth a try, once you make sure that the item costs less than the voucher amount.