Hi Keith
Civil registration (ie the recording other than in the church) of marriages in Ireland only started in 1864. Although some Church of Ireland marriages were recorded before that date. You should ask on the Kilkenny board about what churches existed in Kilkenny at the time. I would be surprised if they had a military chapel. Experts on the Kilkenny board can also tell you if any church records are online. Although how do you know they were married in 1844?
My records have the 56th Foot in Kilkenny for only three months, from June to September 1844. They moved from Gibraltar to Bermuda in May 1851.
I am interested in your use of 'station'. This usually means where the CO was based. It does not mean that all the 56th were in Kilkenny. So where have you got this from?
Ken