I believe there's the Euro Tunnel as well as a number of ferry options, but which can I use to travel with a car between the UK and France, Belgium or the Netherlands?
If there aren't too many options an exhaustive list would be great. If not, what would be the
Related question: What is the cheapest way to cross the English Channel from France to the UK on foot, single ticket?
The shortest crossings are the quickest and cheapest. So Dover/Calais is very popular. And the EuroTunnel train from Folkstone/Calais is effectively the same, but quicker (35 minutes compared with 90 minutes) and more expensive.
However you then have to factor in the drive to and from the crossing points, which costs both time and money. Hence a longer more expensive crossing may suit you better. For example the 10 hour crossing from Rotterdam to Hull is probably more time-effective than driving from Rotterdam to Calais and Dover to Hull.
Other factors:
To cross the Channel with a vehicle, you have two choices: ferry or train. The ferry costs less and takes longer, the train faster and more expensive. Folkestone is the departure point for the Eurotunnel train to Calais; the most popular ferry crossing is Dover-Calais.
Here's an overview of some of the options:
To France, the choices are Dover–Dunkerque, Newhaven-Dieppe, Portsmouth to Le Havre, Caen, Cherbourg, or St Malo; Poole-Cherbourg, Plymouth-Roscoff.
The ferry route from England to Belgium is Hull-Zeebrugge. For the Netherlands, Hull-Rotterdam, Newcastle-IJmuiden, Harwich-Hoek van Holland.
As for convenience, that depends on where you start your journey and where you're heading.
I've just returned from France by car and I've done the trip many times. Each time I've looked at all the various options, EuroTunnel, Calais-Dover Ferry and then the longer routes. Each time the Dover-Calais ferry route has been the cheapest with Dunkerque-Dover slightly behind.
From my experience all the longer routes are MUCH more expensive (2-3 time more usually) but that will depend on what time and day you want to travel. Being closer to the ultimate destination by taking a longer sea route has never worked out quicker than driving from Calais.
Eurotunnel has always come out more expensive.
My recommendation is to check all the options (it doesn't take long) but I suspect that the Calais-Dover ferry will be cheapest. The time difference between that and the Eurotunnel is relatively small and not worth the higher price.
I usually go by price and least hassle.
Summary:
Cheapest - usually ferry from Dover
Quickest - Eurotunnel
Most Popular - Eurotunnel and ferry are both pretty close.
Enjoy your trip and the English roads.
The only crossings from GB to the European continent that aren't mentioned in other answers are the direct ferries to Spain.
Portsmouth-Santander Portsmouth-Bilbao Plymouth-Santander
The ships are a sort of cross between a liner, a cruise ship and a ferry, in that they take cars, like a ferry, but have lots of cabins and facilities like a cruise ship, but are relatively fast and run to a schedule like a liner.
Note that cabins are compulsory on such long journeys that always include an overnight, you can't just sit in a lounge like you can on a ferry.
As others have said, Dover-Calais is the shortest ferry crossing. It also has the most frequent sailings: P&O have 23 sailings/day, and if you buy the right type of ticket (flexible rather than the lowest-cost fixed sailing time) you can turn up whenever and be on your way in about an hour.
Note there are several (2-4 in recent years) ferry companies on this route. Last time I checked, P&O was the cheapest and most frequent, DFDS have fewer sailings.
When planning your journey, check the traffic situation in Dover/Calais beforehand, the ferry company website will usually mention any issues. There have been recent incidents where due to strikes or customs holdups there were very long queues (12h+) on the roads into the port.
From Calais to the middle of the Netherlands is about a 5-h drive, I found it's quicker, more convenient and cheaper to drive to Calais than use the Hook of Holland-Harwich route.
Prices vary massively with season and time of day. Buying a ticket in advance is always cheaper than just turning up (expect at least €75 extra).
Assuming you have a relatively watertight car, you can do it the way top gear did:
https://www.youtube.com/watch?v=YVjo6YOT3Zg
just attach a boat motor to the back, a couple extra buoyancy devices (i.e. empty oil cans) and "drive" across the channel - no need for a silly ferry or train, but rather you end up actually crossing the channel with a car
One further point to consider is that, due to the popularity of the shorter crossings Dover-Calais and Folkestone-Calais, those are far more likely to cause traffic-related delays due to complications related to security, strikes, migrant problems etc. For example, several weeks ago at the start of the school holidays, cars were gridlocked overnight on the main motorways leading to Dover because the French authorities increased security checks at the border control, without allocating enough personnel to compensate.
Over the past few years, I've travelled from West London to Brittany during the peak season and always taken one of the other crossings, e.g. Poole - St Malo, Portsmouth - Le Havre / Cherbourg / Caen, Newhaven - Dieppe. On at least two of those occasions, I know that I would certainly have been delayed had I chosen the Dover - Calais route.
The cheapest option for crossing the channel to France is nearly always going to be from Dover to Calais or Dover to Dunkirk. It's the shortest distance and therefore the ferry companies can maximise the number of crossings per day. Quickest is via the Eurotunnel with around 35 minute journey time. The most popular is Dover to Calais in my opinion some 13 million people used the route in 2015 closely followed by the Eurotunnel which had around 10.5 million. Source France Ferry Booker Other routes are popular with travelers for different reasons. Those living in the south or southwest of the UK may not want to travel all the way to Dover to then head back down to Brittany. A trip from Plymouth to Roscoff or Portsmouth to St Malo may therefore be more favourable.
Mostly popularity is down to need and choice of the individual traveler.
It might be slightly more expensive, if you book in advance, but Eurotunnel wins every time for me:
Quick to load and unload your car onto the train (you stay in your car for the journey) - just drive on and drive off again.
Just 35 minutes to cross.
Up to 4 crossings an hour at peak times (and at least one crossing every 2 hours in the middle of the night).
No weather disruption. No seasickness.
The price you pay is for the car; not per passenger.
And if you arrive late, it is easy to move your booking onto the next available - you will rarely have to wait longer than an hour or pay more.
