Speed limits (does nobody admit to knowing them?) 70mph on Dual and M/way, 60 otherwise unless indicated. 30 in towns unless indicated.
Newcastle to London the A1 is usually a better bet, but the M1 might be easier to follow. Are you planning to stop in London? otherwise use the M25 and M20 to Dover. The tunnel is on the M20 before you get to Dover and the ferries are all out of Dover Eastern docks. Allow 6 hours Newcastle to London and at least 2 for London to Dover. If it's wet allow more time. Expect inexplicable traffic jams and delays and you can't go wrong. Watch out for speed cameras...
Personally I'd use Eurotunnel (quick but can be pricey) or Speed Ferries (very simple fares structure).
If you're going to Nürburgring, are you just looking or expecting to drive. I don't know if it's open, but in any case it's in the Eifel mountains and gets a lot of snow.
All the channel crossings can be booked on the internet: Check ou P&O Ferries, Sea France, Speed Ferries and Eurotunnel.
Lastly - I'm puzzled because your location says "Germany".