It's not easy to buy a really raw milk (not pasteurised) in Poland.
Generally, there are 3 types of milk available in the shops. Within each of these types milk of a different fat content is available, which is usually distinguished within the types milk of a given company by different colors on the package.
1. UHT milk - usually sold in cartons, you can find the UHT abbreviation on it - in a more visible or a less visible place:
Stays fresh for the longest time, don't have to be kept in a fridge before opening, but it's most processed (it's heated to about 135-140 deg. C and then quickly cooled down to about 20 deg. C) and, probably, most unhealthy.
2. Pasteurised milk sold in bottles - described as "pasteryzowane":
Stays fresh much shorter, has to be kept in a fridge, but it's less processed (it's heated to about 60-90 deg. C to kill germs) and, probably, less unhealthy than the UHT milk.
3. Pasteurised milk sold in plastic bags - also described as "pasteryzowane":
When you leave it for a longer time in a mug in a warm place, it will not get spoiled, but soured. I don't really know how it's different from the pasteurised milk from bottles, but it's somehow more similar to the milk "straight from the cow". This type of milk is rather not met in chain supermarkets, but it's possible to buy it in local shops.
The last type is fresh milk "straight from the cow". Some time ago in bigger cities, near shopping malls, vending machines selling such milk started to appear, but AFAIK, they disappeard as quickly as they appeared. I know that they are still in some places - you need to google under the term "mlekomat". You can also look for it at local street markets.