Nordshleife, also known as the Northern Loop of the Nurburgring is located in the town of Nurburg, Germany. The town is close to Adenau, located in NW Germany and within easy reach of the UK. The journey time is under 5 hours from Calais, and approximately 490km.
Taking a route along the motorways it is possible to reach the Ring in under 5 hours from Calais as it is just under 500km. However this route is very dull and uninspiring. There are alternatives that go through some of the most scenic parts of Belgium and Germany. The route I have used several times does take up to an hour longer but the experience is worth it. Winding B roads, ascents and descents across the hill regions and less traffic.