I use the debit card all the time abroad. I've got a holiday money float in most of the account currencies which I top up when there is some fx volatility, but have found the conversion to be fair when I do need to convert on the fly. Hsbc global money (UK/Jersey multicurrency equivalent proposition) is a tiny bit better at least for non-euro European currencies but it was a small difference when I looked into it.
Also don't discount using payme unionpay where its accepted. FX spreads are tiny as UP gets heavily regulated by our overlords up north.