Within the 28 countries of the European Union, yes, roaming charges are no more. You do not need to set anything up; wherever you are in the EU, you will be treated as though you are in your home country. From 15 June 2017, the European Commission clamped down on over charging for roaming. The slogan used is “Roam Like at Home”, and Brussels has promised “no more shocking bills”. Your provider now has to charge your usual domestic rates or takes your roaming consumption from operator simply charges you domestic rates
No one knows. As citizens of a non-EU country, the British will have no automatic right to free roaming throughout the EU. It’s possible that the Brits could negotiate similar measures yet the phone companies may reintroduce enormous charges. Unfortunately, it seems to be wait and see and keep your fingers crossed, as with the rest of Brexit.