In general, the young are more liberal than the old. Scotland in general is a more liberal country than England, which is becoming increasingly conservative as Cameron continues the job started by Thatcher. A lot of younger Scots would like Scotland to be independent so they can model the country of the socialist Scandinavian countries which are more prosperous than Britain.
As it stands, they're wedded to the economic policies of England, specifically the hyper-conservative South-East which dreams of modelling Britain after America, and selects policy mainly for the benefit of London's finance industry, even at the expense of industry in the rest of the country. A shipyard in Scotland might lose all its foreign orders and shut down because of London's politicians fiddling with the currency, or a Glasgow businessman might be unable to find a premises due to high property costs, deliberately inflated to benefit the banks and promote debt-based consumer spending to benefit the retailers.
I don't really know anything about Quebec, but Canada is a federal country, and doesn't have one province with 5/6ths of the population so the same issues don't apply.