I find that a ferry crossing is better than the tunnel because it is an enforced driving break of a decent period and sets you up nicely for the next leg - only use the tunnel on an urgent job where time is of the essence - down time is important.
The best company I have dealt with for ferry crossings is 'My Freight'. Get an open ticket so you don't have to hurry for a particular ferry ( no worries with delays and speed cameras or police ) Book to go DFDS as this is a lot cheaper than P & O ( the service is a lot better than it used to be) and for the last few months the meals have been free ( they won't say when this offer ends - it was supposed to be the end of Oct but I have been over 2 or 3 times this month and it is still going ) with the usual amounts of free expresso to keep you going at the other side. When you book your ticket tell them that there are 2 drivers and your customer will have a free meal too.
I have used most of the ferry bookers and 'My Freight' prices are very competitive they will text you the confirmation number promptly so you are not hanging about waiting. As a rule I never book tickets before I have got the load on board just to be sure that the job is happening but this has given me problems with bookings not being made in time for crossing with other companies.
Winter tyres- Essential over there but I would say essential over here. Everyone needs tyres on their van so they might as well put winter tyres on - miss a couple of days work and it has already cost you the price of the tyres. Pay your excess and you really are out of pocket.
I have used mytyres. co.uk for the last few years. The tyres come from Germany the price is a delivered vat inc price and it usually takes less than a week for them to arrive. Bridgestone Blizzak is my tyre of choice my order for 4 cost me £ 385.20 ( inc VAT and p&p) These work well and last well on my sprinter. Put them on as soon as we have more than a few consecutive nights of frost then run them all winter until they are down to the min by that time daffodils are out and old rims go back on. New winter tyres every winter - replace the others as needed.
Make sure that you have enough gas for your stove as the longer thinner bottles that fit in your 'normal over here stove' aren't so widely available over there ( especially in Scandinavia ) and you may end up having to buy a new stove to suit their fuel.
As previously mentioned make sure you are bulletproof on your paperwork Vehicle docs and manifest. Make sure that you have your customer sign the manifest to say that alll the goods are his, he knows that the usual things are illegal and that he takes full responsibility for the loads contents.
If you are lucky enough to get a return load the same applies don't be greedy and assume that it is pure profit. If you haven't had the customer sign a disclaimer the illegal goods are yours as far as customs are concerned. If in any doubt about ANY load coming back in to the Uk inform customs BEFORE you enter the UK on the phone get the person you speak to's name and ask for a reference number for the call and then you will get stopped but you will be in the clear and they will be after the sender not you ( happened to me last week gut feeling proved to be right )
Money is cheapest out of a cash dispenser as you are only getting out what you need and exotic currencies like Francs, Kroner, Lira etc always disapear before you get a chance to use them A decent amount of euros is not a bad idea as a lot of places not in the euro will take them if need be.
En Route Belgium and Luxemburg are probably the best prices for your fuel ( lux being the cheapest by far. If you haven't got a European fuel card use you credit card rather than cash - you will get a better rate and if you get a naughty person in the fuel station they aren't emptying your bank account and you can get a refund from your credit card company.