I can confirm, when I first came to the UK four years ago, only major retailers seemed willing to accept my Canadian CC, and even then, the cashier usually had to call the manager to confirm that it's ok.

Another thing I have to credit Europe with is the lack of proprietary debit card systems like Interac or Plus. It's all done via Visa/Mastercard Debit, so you're never forced to do your online shopping on credit.