From the 1st January 2021 you will need to check with your phone operator before you travel to the EU regarding data roaming charges.

The guarantee of free mobile phone roaming throughout the EU, Iceland, Liechtenstein and Norway has ended for some UK operators, therefore some mobile customers are likely to incur data roaming charges when in Europe. Check with your phone operator before you travel to find out about any roaming charges you might get from 1 January 2021. A new law means that you’re protected from getting mobile data charges above £45 without you knowing; Once you reach £45, you need to opt in to spend more so that you can continue using the internet while you’re abroad. Your phone operator will tell how you can do this. For more information visit the gov.uk site.