You CAN NOT fly an "N" reg aircraft across ANY international border(outside the country of your licenses issuing authority), including inside the EU if you are not type rated on that airplane on your FAA certificate, irrespective of what JAA/JAR license you have. As was said, if your license was issued in the UK that is the only place you can fly the "N" reg machine without a full FAA type rating irrespective of it being a Part 91 flight.