Good Morning, neelawson.
I, too, am the son of a Polish father, from a similar area of Poland, in my case Katowice. Fortunately my father lived here, in Britain, from 1945, for the rest of his life with my mother and his children.
Why your father did not stay with your mother we can only speculate, but two reasons come to mind.
The first being that he was forcibly repatriated.
The second being that the Red Cross had traced him, for his family in Europe, who your Father may well have thought were dead. The Red Cross may have records still.
If you have not already seen this thread, it may be of help.
https://www.rootschat.com/forum/index.php?topic=806804.9If he came to Britain towards the end or at the end of the war, into an assimilation camp, I would have thought he would have moved on to live and work in the general community, perhaps on your family's farm, by the time he knew your mother.
He may have attended a local Catholic Church.
He may also have been here during WWII serving with the Armed Forces, for example the RAF.
With regard to your distant relatives your DNA has identified, FamilySearch has access to Church Records in Poland. However, they may not be complete, as I could not find the records of my family members that I know about.
There are also the commercial companies, such as is featured on ITV's Long Lost Families. I have no experience of these.
I wish you luck in your search.
Dzień dobry,
Stefan