I've never heard of Indian grocery stores in Poland,
There are a few established Indian shops around Warsaw a very good one in Raszyn, and some Middle Eastern ones. Plus a new halal butchers. Makro in Warsaw also have a good range of Indian things.
There's also a couple of online shops.
In Gdansk, if the one Doug mentions is too far or doesn't have the right product, the online one could be a good option. littleindia.pl/lang/en