Will an iPhone 16 Pro from Poland work in the UK?

Hi All

My mother lives in Poland and she wants me to take the phone purchased in Poland on a contract basis to the UK where I live permanently and use it to contact family in Poland.

My question is whether it will work in the UK and will I be able to use my SIM card (EE) and SIM card purchased with the phone in Poland at the same time 🤔?

[Re-Titled by Moderator]