Don't ever use Winter tires in combination with all-seasons ... you won't be doing you're car or the tires any favours. Use one or the other. In addition, using chains can damage you're car and allot of companies DO NOT recommend using them. Just make sure you have good tires.
If you're tires are reasonably good and still have at least half the tread left to them .. then go on your trip and don't stress about it. However, going over such a long distance, I'd consider replacing you're tires with a set of new all-seasons.
If you're not going to use the winter tires for any other reason than this trip, why buy them? A good set of all-seasons will be fine. I've lived in most of the Eastern provinces including Ontario and if its snowing bad enough to make it difficult with a good set of all-seasons; then you shouldn't be on the road during that time anyway.
However, if you have the money ... go for it, it's never wrong to error on the side of caution. I travel for a living and can attest to that.
Check your owners manual, if it doesn't recommend what size winter tire to use .. then I'm positive you're VW dealer can. They'll know what's best!!! But just get a recommendation, I'm sure you'll pay far less for the same tires at a local tire shop.
Best of luck, have a great trip.
P.S. A Good Winter tire is best for traction, chains only provide definitive grip on ice .. that's about it. A good winter tire however will grip ice as well as pavement. The Nordics aren't bad .. if you really want added protection .. get them studed!!!!!