According to the IGI Thomas Wade married Isabella WADE about 1810.
This entry has the notation "Record submitted after 1991 by a member of the LDS Church."
There is also another entry that states Thomas Wade married Ann WADE about 1810. ALSO a User Submitted entry.
This user has provided absolutely no proof whatsoever of the marriage, no exact date, no church, not even a surname for the so called bride. In other words the probability is that this user has looked at the 1841 census without due care and made an assumption that Isabella was Thomas's wife.
They have also posted the births of the children, with the dates "about" in each case, once again giving absolutely no proof whatsoever except their own say so.
As far as I see it the clues that you have are from the marriage certificate of Catherine - including probably her brother Samuel who is witness. Her family are staying with her other brother Thomas, and these are all linked together in the 1841 family, where it is suggested that the eldest person, apart from father Thomas, is Isabella who (as ages are rounded down in the 1841 census) can be at most 35 years old and the next eldest, presuming he is Thomas's child is young Thomas who is 20+ years old. I believe it highly unlikely that Isabella will be the mother of young Thomas, so very likely another sibling.
The Online Parish Clerk's site has a marriage TRANSCRIBED from the Parish Register. This information is more more reliable, although should still be verified by you by sight of the actual entry.
Marriage: 4 Jun 1842 St Augustine, Liverpool, Lancashire, England
Thomas Henry Wade - Full Book Keeper Batchelor of Liverpool
Elizabeth Hughes - Full Spinster of Field St
Groom's Father: Thomas Wade, Inn Keeper
Bride's Father: Roger Hughes, Inn Keeper
Witness: Margaret Thompson
Married by Licence by: T Tattersall Minister
Register: Marriage 1837 - 1860, Page 44, Entry 88
Source: LDS Film 1656013
I believe the occupation of both groom and his father confirm that we have the right family in the 1841 census. You should also confirm this by means of the birth certificate of one of the children.
Again from the Online Parish Clerk site you can check the baptisms of two of the children
Baptisms: 9 Jan 1845 St Peter, Liverpool, Lancashire, England
Thomas Wright Wade - Child of Thomas Henry Wade & Elizabeth
Abode: Mill Rd Everton
Occupation: Book Keeper
Baptised by: Tho. MacGill Curate
Register: Baptisms 1844 -1846, Page 16, Entry 128
Source: LDS Film 93884
Baptisms: 4 Feb 1847 St Peter, Liverpool, Lancashire, England
John Bateson Wade - Child of Thomas Henry Wade & Elizabeth
Abode: Mill Rd Everton
Occupation: Book Keeper
Baptised by: A J Tomlin Curate
Register: Baptisms 1846 - 1847, Page 357, Entry 2851
Source: LDS Film 93885
Unfortunately the baptisms don't give Elizabeth's surname but it's fairly easy to be sure about the entry for John Bateson Wade birth Q4 1846 West Derby 20 982 which will confirm his mother's name.