Hello Lyn, I searched Roots Ireland and there is no Bridget Garner to be found with father James. Garner is a variant of Gardiner and there are are of those in Laois, I found only 2 with father James Gardner, one Margaret was born in February 1840 in Raheen parish, mother Mary Cassin, she is the only child of these parents I see from 1830 to 1850, why it may be relevant is that Raheen is the parish next to Mountrath and it is possible the family lived near the town of Mountrath and would say that is the homeplace, as it is the nearest place of consequence but we are only surmising here. The other birth is an Ellen in 1831 with mother Judy Larkin and the parish is Mountrath.
I looked in Griffiths Valuation and see Gardiners in the area but oddly most entries have them as landlords rather than tenants, it was carried out about 1849 or 1850. I cannot see a marriage but previously searched areas of Laois and found records of some parishes start into the 1840s so may not be available.
I believe there is an active Facebook genealogy page for Laois if you want to try, apply to join.
Good Luck
Pat