Hi,
they do ship to germany, so I think the ship to the UK. Try
http://uk.digikey.comYou could try the Digikey part number 296-12973-1-ND, which is a TI CY74FCT16543ATPACT. They are on stock and have a minimum quantity of one. Looking at the data sheet they look the same as the IDT one on your card.
One problem with Digikey: When you order only a few parts, handling & poastage is quite expensive. I.e. 4 of these part cost about 3 pounds, shipping and handling would be 17 pounds.
greets
christoph