Maggie
I hope you'll allow me to summarise where I think we are. The original question is, essentially, "what becomes of William Tuckwood baptised 16Nov1812 Nottingham St Marys.
We are fairly sure that he is not any of the William Tuckwoods we can find in the East Midlands in the 1851 or later census.
There is a William Tuckwood married 1829 Radford to Sarah King. Newspaper evidence in 1834 places them in Nottingham, but we are unable so far to trace a William Tuckwood married to a Sarah in any census.
We do have in 1841 William Tuckwood of Greetham, aged 30. However wife given as Jane aged 20, children Elizabeth 4 and Mary Ann 11 months. Given the wife's name and age of eldest child I don't think this could be the 1829 marriage.
So as things stand this 1829 couple seem to vanish.
I think what needs to established next is the identity of the William Tuckwood of the 1829 marriage. It seems a bit early to be William bapt 1812. Does the full record have anything more than we curently know? If we had an age for that William, or Sarah, we might progress what happened to them.