You’re assuming he spends all his income in the EU from the U.K. and pays by visa/MasterCard.
I dont buy anything from the EU for personal stuff, it's never any cheaper and they don't offer anything I cannot obtain in the UK.
However should I go to Europe for a holiday that's when it will cost, but I'm sure I can circumvent that by taking cash with me. Though I would then have the worry of losing my holiday money.
For work what we purchase from the EU is all paid by Bacs so again not a worry for us.