Series 2 of Inside No.9 doesn't have official, DVD made, commentaries. But Steve and Reece recorded in their office these "homemade commentaries", and shared them online, on a SoundCloud account. The account has disappeared since then, but it would be a loss to no longer have these commentaries.

They first recorded episode 2 of series 2, 'The 12 Days of Christine', and then this episode (episode 1 of series 2).
I would recommend, for a better experience, to listen to the commentaries in the order of recording.
Enjoy!