Tracing Teresko ancestry, where to start?

Hi, I've posted on here before and I got some decent answers but not enough to get me any further.

I'm trying to search back to my great-grandad Piotr and go further back starting from him. I know little details such as his first and last name (Piotr Teresko) I know he got married in England to Lillian Johnson in 1949 (camberwell, London), I also know his fathers name (Plato Teresko) However...I'm just unsure of their origins and whether or not they are infact truly Polish. There are some links to Mława, which I believe is where Piotr was born or he lived there before he came to England.

Any ideas on how I can expand this family line at all?

Many thanks! :)

I looked in the USA census records available for free through the family search website and there are many people with this surname. You might look over some of the census information to get an idea where people said they were from. Some say Russia, many say Poland and others say Austria. Poland as a country did not exist at some of these times and so if they lived in the Russian part of Poland their origin would be listed as Russia. Austria could be the southern part of Poland. You can narrow your search down to other countries such as England or other categories. If you find them in England,then you go back following the trail. Look for immigration records to England. You can also send for death records. For example, if Plato also lived in England and he is the most distant ancestor, find his death certificate. The informant may list the country of his origin.

Piotr Teresko was born in Mlawa to Maria and Plato. Plato died when Piotr was a baby. His uncle Valentine helped his mother raise him.

When Germany invaded in1939 Piotr was taken prisoner (at the age of 15). His mother was shot by the Germans. He survived the war and joined the British army (Free Polish Army). After the war, he moved to London, married Lillian and raised a family.

Yes, his family was Polish. Wealthy landowners. Don't know what happened to them.

Hey. Long time since I've checked this. How did you know his mothers name was Maria, and his uncle Valentine?

Is there any possibility his family was Jewish?