Law / Polish wife in the UK cheated on me. Divorce - what now of the kids? [15]

We have been married for over 10 years. I recently found out my wife cheated on me(she is polish). We have 2 young kids. We have been married in Poland (registered in church).

Where would one file for divorce/child custody? Is it UK, where we live or Poland where the wedding was registered. The young kids have been living in UK since their birth. Your help is much appreciated.

Are UK/Polish courts likely to consider infidelity in determining anything.

Law / Query of Polish Wedding Register - is it possible to get it online? Or only in person in Poland. [2]

Is it possible to query the wedding register online(for a church ceremony done in Poland in 2003). Or do we have to go in person to the registrar office in Poland. As I dont live in Poland this would make it very inconvenient and expensive.

If its not possible to do this online. Would you recommend we do this via a lawyer.

Can someone help, even if its a polish website only. English website would be great though.