For Valentine McAvoy B 1845 (exact), somewhere in Ireland, with the father's forename unknown, I found 1 rcd, 1845, Co. Laois. Father's forename was Edward.
For Valentine McAvoy M ????, Co. Laois, I found 1-church and 1-civil M rcd, Co. Offaly, both in 1878, Killeigh RC, and Killoughy CP respectively.
For Jane Heffernan M ditto, I found ditto.
For Jane Heffernan B 1845 +/- 5 yrs, Co. Laois, or Tipperary, I found 3 rcds: 1840 (Arles) Laois, 1844 (Tullamore) Offaly, and 1844 (Tubber) Offaly. Father's respective forenames wereTom, Anthony, and John. A view of the detailed rcds SHOULD reveal the mother's names. This info is useful in finding earlier B/M rcds for the parents.
For John Heffernan M 1840 +/- 4 yrs, Co. Offaly, I found 2 rcds: 1838, and 1844. Both were in Tullamore RC parish.