Dear Patsy,
I have had a look at the 1861 census for the Byker area (District 6) and I think I have spotted the entry for Nathaniel & Catherine at Byker Fields Ropery
Ref: RG9/3833 page 47 Folio 67
Nathaniel Hall Head Married 31 Rope Maker Newcastle, All Saints
Catherine Hall Wife Married 21 - Newcastle, All Saints
Mary Ann Hall Dau. Single 8 Scholar Newcastle, All Saints
Alice Hall Dau. Single 4 Scholar Newcastle, All Saints
Isabella Hall Dau. Single 3 Scholar Newcastle, All Saints
Elizabeth Hall Dau. Single 1 - Newcastle, All Saints
I am not sure about Catherine's age it does look like 21, but perhaps it should have been 27 otherwise she was rather young to have an 8 year old daughter. The other possibility is it was Nathaniel's second marriage. When you get the marriage certificate it might make it a bit clearer. I also think Nathaniel wanted a boy, because 10 years later in 1871 the family had grown!
Byker Village - Ref: RG10/5106 page 60
Nathaniel Hall Head Married 42 Ropemaker Newcastle
Catharine Hall Wife Married 39 - Newcastle
Isabella Hall Dau. Single 13 - Newcastle
Elizabeth Hall Dau. Single 11 - Newcastle
Sarah Hall Dau. Single 9 Scholar Newcastle
Francis Hall Dau. Single 7 Scholar Newcastle
Catharine Hall Dau. Single 5 - Newcastle
Margaret Hall Dau. Single 3 - Newcastle
Nathaniel Hall Son Single 4 mths - Newcastle
A boy - success at last!
When you do get the marriage certificate, which should give the names of the fathers, and if it turns out that Nathaniel's father was also called Nathaniel then this entry on the 1851 census might be of help.
Prudhoe Street, Newcastle, St. Andrews Ref: HO107/2405 page 40, Folio 440
Elizabeth Davison Head Single 61 Cow Keeper Newcastle
Cuthbert Davison Brother Single 39 Cow Keeper Newcastle
Nathaniel Hall Brother-in-law Widower 47 Commision agent Gosforth
Catherine Murray Serv. Single 15 House Servant Wylam
There are a few Catherine Turnbull's on the 1851 census, but unfortunately they all seem to be working away from home as servants, so no family around them to check the names of their parents. Perhaps when you have more details you might be able to select the correct Catherine.
Good Luck with all your searches, and welcome to this very addictive hobby!
Best Wishes,
Patsy - yes another one!