Growing up in the late 70's and early 80's the Jam were my Beatles.
The Greatest Hits package is a great place to start with, as the Jam were really a great Singles band.
When the first Greatest Hits package (called SNAP!)was released back in 1983, it came with a large volume of standout album tracks and B.sides which have some of the Jams finest 3 minutes, but I can't recommend this enough as a great album to buy to start with, Tube Station, Eton Rifles, Going Underground ,Thats Entertainment, Town called Malice and Precious are masterpieces of Singles.
For a snapshot of English life, you won't find better.