Visas and Shipping
N.B. Shipping your own motorhome from Europe to Canada only makes sense if you have a specialized vehicle and you plan to spend a long time there. For a short visit it makes more sense to hire a vehicle in Canada or to buy one there and sell it when you leave.
This page lists some of paperwork, costs and logistics of shipping your own motorhome to Canada. Note that it has been written before I have succeeded in getting myself and my motorhome into Canada, so it may well be incomplete. Getting into Alaska (i.e. the USA) will be covered later.
If you have a UK passport (British Citizen and most other types) and you intend to spend six months or less in Canada then you should not need a visa, but you may well need a return air-ticket before an airline will fly you there.
In 2012 - "When you arrive in Canada, the immigration officer will decide whether you can be admitted to Canada and, if he is satisfied that you intend to stay only temporarily, will decide how long you are allowed to stay. Unless otherwise specified, you are authorized to stay up to six months. You must leave Canada by that date or else, at least 30 days before that date, apply to prolong your status."
Carnet de Passages en Douane
You should not need a Carnet de Passages en Douane to take your motorhome into Canada.
The cost of shipping a motorhome (by RoRo) from Europe to Halifax NS in 2012 is about £53 UKP (65 Euros) per cubic metre. (It may be quoted as a lot less than this but when you add the various surcharges it will end up around this figure). This translates into between £1500 and £3000 UKP depending on the volume of the vehicle. There are ships leaving Europe for North America every week. (Note that these costs are one-way only.)
In addition to the shipping cost you should also consider (but not necessarily buy) marine insurance which will be charged at around 1% of the value of the vehicle.
There are three major areas of concern related to shipping a motorhome from Europe to North America, firstly the cost, secondly the complexity of the paperwork and thirdly the common requirement that the vehicle be empty! (Yes: most shipping companies will not officially allow any contents in a vehicle being shipped. In practice many people (myself included) do leave contents in their motorhome when it is shipped, but you risk having the vehicle rejected at the port if it is inspected! Note that it is almost always the shipping company, not customs at the destination, that require the vehicle to be empty.)
The most frequently recommended shipping company on this route (and the one I'm using) is SeaBridge. SeaBridge are based in Germany and arrange shipping from either Antwerp or Hamburg. Their main claim to fame is that they specialise in shipping Motorhomes (and are thus able to help with the paperwork) and they explicitly permit motorhome contents to be shipped.
SeaBridge will email in English, and are generally responsive to questions. However their very comprehensive "how to ship your motorhome" documentation is in German only. SeaBridge have their own "agents" at both Antwerp and Hamburg who will (presumably) help sort out any problems when you deliver your motorhome to the port two days before it is due to be shipped. They also have an agent in Halifax NS who will assist in getting your motorhome out of the docks there. In principle SeaBridge will arrange shipping out of Liverpool UK, but they do not have an agent there and you would (presumably) be on your own if there was any problem with unexpected "contents".
SeaBridge also offer vehicle insurance in Canada and the USA and help with getting Canadian/USA gas (propane) bottles to fit your (European) motorhome.