Hello everyone,
the only correct official precedence for a Polish military would be as follows:
Krzyż Walecznych
Medal Wojska
Krzyż Pamiątkowy Monte Cassino
1939-1945 Star
Italy Star
Defence Medal
War Medal 1939-1945
It should be noted that the recipients who had both Medal Wojska and the War Medal were not supposed to wear them together (but they often did).
I also do not think the medals could have belonged to a Brit, as both Medal Wojska and Monte Cassino were conferred exclusively upon members of the Polish Land Forces and not upon the Allies. Such a set of medals was typical of a soldier of the 2nd Polish Corps, who had participated in the capture of Monte Cassino in May 1944.
Judging from the photos, the ribbons look genuine, although the Monte Cassino ribbon should have a bronze "Monte Cassino" bar upon it.