skills on Family Tree Circles

Hi Can anybody help me with Herbert Thomas
In the 1851 Census he was a farmer at llwynyrhebog farm near Cwmifor
Lower Mandeilo llandeilofawr
Herbert was 30 and his wife Margaret was 30 and they had a son William
8months old.

Nothing is found about them until 1871 when they are in the 1871 census
Herbert was an innkeeper at Corner House Carmarthen Street Llandeilo
Herbert age 50 Innkeeper - Margaret age 46 - William their son age 20
-Elizabeth their daughter age 11.

They are then lost again.
I am also interested in what I believe is their son John Thomas b.
8.4.1854 ( link to Herbert Thomas in the Family Bible)
John married Ann Thomas (Ann was from Llanfair clydogau) 14.7.1877
but there is no trace of the marriage .
They then appear in Martin Street Clase llangyfelach in the 1881
census and they are easy to follow then.
I can however find no details of John before 1881