Hi Grenville.
In France and Italy, not sure about Spain, as we haven't been for a while.
When travelling from the UK we take just enough Euros to keep us going until we can get to an ATM in France.
Like Clive we use our Nationwide flex account debit card in ATMs which can be found at most banks and supermarkets too. Nowadays most French ATMs accept UK Chip and pin cards without any problems. That has been our main current account for over 20 years anyway. We keep any spare cash in a N/Wide online Esavings account and transfer it to our Flex account when necessary. The Flex account online service means that I can check my account and move cash around, as above,online whilst abroad. There is, also, a N/wide Phone banking service which I have used from France when there has been no internet link readily available.
We, also, use Nationwide and Post Office credit cards as these do not charge any weighting when converting from Euros to sterling - most other card providers do. Again these cards are freely accepted at most supermarches and petrol stations. Many auto pumps at petrol stations now accept UK C&Pin cards without any bother.
My wife and I now have our own seperate N/W credit card accounts, as well as being cardholdes on the others account, as a theft a couple of years ago left us cardless in Italy. We now, also, keep one of the cards hidden in the 'van as an emergency back up.
I hope this helps.
Tim