Is this your own car?

If not, is it rented? Do you have permission to take it our of the country? And to the UK? Do you have idea what the drop off fee will be?

Do you have good maps of the entire route?

General advice:

Stop at least every 2 hours to stretch your legs.
Learn the meaning of all the international travel signs.
Have detailed maps of any towns you are driving through (and where you plan to stop to spend the night) - assume you will spend at least 2 nights on the road - since this is a VERY long drive

Try viaMichelin for driving information such as toll roads, distances, best route, etc. You may want to pick up an International Driving Permit for your local AAA office.

I have heard it has snowed a bit in Poland. But i am also intrigued how you are intending to do this trip? Most hire car companies do not allow you to take a car on a ferry. Besides you will have a LHD car in Britain they drive on the opposite side of the road that make be the hardest part of your trip

Be prepared that in Germany the A2 West of Hanover still has quite a few construction sites. It can get very slow.

Also in Germany, once you approach the Wester industrial region commonly referred to as "Ruhrgebiet" (roughly between Dortmund and Duisburg), traffic on the many different Autobahnen can get very dense, especially during typical rush hour times in the morning and late afternoons. You may want to time your journey so you don't hit that area at that time.

I recommend crossing into the Netherlands at Venlo and then to proceed via Antwerp (make sure you don't miss the ring road and follow the signs for the A14), Ghent and Bruges to the French coast. Mind the radar traps between Dunkerque and Calais.

Personally, I prefer a ferry crossing over the train, as it gives you a nice break with fresh air.
Convenient ferries depart from either Dunkerque or obviously Calais.

The Dunkerque ferries depart only every 2 hours and crossing is 2 hours, so some 30 min. longer than from Calais, but you save some 10 min. of driving, so the disadvantage is down to roughly 15 min. Prices on the Dunkerque route normally are cheaper.

If you feel like booking ahead, Dunkerque may be a good option.

http://www.norfolkline.com/ferry/

If you just want to wing it, Calais may be preferrable as there are more departures.

http://www.poferries.com/tourist/
http://www.seafrance.com/cs/Satellite?pagename=Wrapper_SF_Pax_Uk&childpagename=SF_Pax_Uk/Layout&c=Page&cid=1233760949014

Bear in mind that you would have to be at the quay approx. 1 hour ahead of departure if you don't have a ticket yet (and that's cutting it close, some 75 min. may be better), some 45 min. before if you do have a ticket. So, if you wing it, and you realise that it'slikely going to be tigth for a Dunkerque sailing, you may want to proceed to Calais.

Seafrance sometimes has marginally quicker crossing times, but in general that may level out depending on arrivals of other ferries in Dover (narrow entry into port). Tariffs are depending on demand, my impression was that Seafrance from Calais is often a bit more expensive than P&O.

If time is of the essence, try the train shuttle to Foksstone.

http://www.eurotunnel.com/ukcP3Main/ukcPassengers/

Driving on the left in the UK should be less of a problem than some posters may lead you to believe. As you are part of a closed system, driving should be easier than walking, actually. Just remember to stay in the left lane on the motorway and to overtake on the right.

Depending on where you want to go in London, consider getting off the M20 at the M26 junction and to proceed on the M26/M25 if you are headed West.

In general I would recommend using a satnav, preferably with a TMC option as that will guide you around traffic jams and will be handy in the Ruhrgebiet area (if one freeway is jammed, just switch onto another one and let the satnav work it out) and London in paritcular.