After listening to this, I went to the Internet Archive and found Milton's Areopagitica read by Thomas A. Copeland:
It takes a little over 3 hours and you can stream it. The background information of Milton's life is at the end for some reason and should probably be listened to first.
The first five minutes are a bit of a shock: You have to change gears to allow for the educated, pre-sound bite era, but after that it's fairly entertaining. He brings every possible argument against censorship to the table and is by turns flattering, cajoling, realistic, wise and snarky.
I'm not sure what he'd think of modern day England: The leaders are so impervious to argument and drunk with power that he would probably default back to regicide.