There exists a standalone episode that was never filmed. The episode is called 'Tramspotting' and was written by the show's creator, John Rooney. The script follows stoners Rab and Jake on the trip to Amsterdam referenced in episode 6 of the first series.
Paul (jimmy) & stephen mcole (rab) are brothers in real life
Paul McCole wrote all songs performed by his character Jimmy.
There is a podcast series with the full cast talking about the full two series by Jibber Jabber Podcast.