It is years since I've lived in the Great White North and a few since I last visited - for the 2010 Winter Olympics - yet I feel my comments/thoughts/observations remain valid.
What sort of advice are you looking for? (from a parental perspective or from hers?!)
At C$80k, I could live very, very comfortably. Van may be considered expensive by north american standards but compared to London it will seem cheap.
Taxes are considerably lower. Healthcare needs to paid for - but I would imagine for her line of work this will be covered by her employer or directly deducted from her pay, so she won't miss it.
And talking of tax, VAT is handled differently and may at first seem confusing. Retail prices do not include Provincial Sales Tax (PST) nor Canada's version of VAT, GST. In BC, PST =7%, GST = 5%, so cost price is 12% more than shown.
There is no such thing as free banking in Canada. (Bank profits are good and do not require government support!).
Accommodation. This is relatively expensive, and like all cities, the 'better' residential areas are more costly. Van is a fast growing city and a very popular location. House prices reflect this. It is one area I would pay attention to. As noted above, commuter traffic can be a nightmare e.g. from North Van to downtown. If her work is located downtown it needs careful consideration.
Climate. Umbrellas are not required any more than the UK! It is a temperate oceanic climate hence it rains. But it does not get cold or snow like the rest of the country- often. Snow may be found in winter nearby and I'll come to that.
Culture. There is plenty and diversity. If she wants. Just different from London/Montreal.
Food/Wine. Both thriving in Van. There are good, creative chefs and BC wines are excellent. (Most made a few hours drive east in the Okanagan Valley and would highly recommend a visit!)
Transport. Downtown cars are an encumbrance. Bike infrastructure is improving all the time. I am not up to speed on the efficiency of public transport - I understand the rapid transit to be good. Getting away a car is considered a necessity. Both cars and gas (petrol) are much cheaper than UK.
Leisure. D1 enjoys mountains, surfing, skiing, hiking and biking. She will have access to all these in an abundance she will not believe. Most Brits are aware of the Whistler complex, rated one of the best in north america, if not the world. However, there a plenty more. Likewise skiing, including proper Nordic skiing not just the lazy Alpine skiing. (yes, I'm biased!). She could hike for days without seeing another soul if she desired. Biking - mountain or road? Or trendy gravel? Plenty of places to choose from. The Sea to Sky Gran Fondo has quickly become a huge event in a short time frame held in september each year. And even surfing is well catered for if you where to look.
BC is vast. As is Canada. Van is closer to Japan than western Europe. This is why vehicles (or boats or planes - some places are only accessible by boat or small plane) are required to get away from the city to your very own adventure playground quickly. If you want to hike or fish for days without coming across another human, it is possible.
I visited Van twice to consider relocating but it was not for me, at those times. Most folk feel the exact opposite. It is a young person's paradise. People are generally very friendly and tolerant, as is the canadian way. I feel she will have no difficulty meeting other young people - I have a young relative who has just graduated from UBC; I know a young Brit who lives in whistler; my nieces are 18 months into a 24 month stint at Panorama, BC - one has become an adrenaline junkie!; others are older.
Ask away! And feel free to PM me if you would like some young folk contacts.