Hi @oateem,
welcome to our English Community. Nice that you would like to inform yourself while travelling within Europe.
Which Roaming-package is included in your tariff? Just have a look in “Mein o2” at “Tarif & Optionen”. You will find there also a subheading “Auslands-Optionen”.
If you already have the package “Roaming Basic” you do not need to worry. You just can use your mobile internet in the same way as in Germany. You do not have a time-limit. You just use your data-volume for the month.
But please consider our Fair Use Policy that you find here: EU regulations
As Great Britain is no part of Europe anymore, please inform yourself concerning the payment from an English Bank.
As you have closed your German Bank, I stopped now the direct debit from your German Bank-account.
I hope I could help you with this information.
Loving greetings,
Tobias