Linda,
are you targeting Hexham church records for the marriage because Thomas was born in Hexham ?
Where was Elizabeth born ?
Anyway to find or not find his marriage in Hexham, I journeyed to Northumberland County Record Office (Woodhorn) at great expense in very stormy weather.
Well not quite true, but I did look at the Hexham marriage index 1540-1837... on GenUKI web site.... www,genuki.org.uk The index is in date order rather than surname alpha order.... I could not see your couple... but better look yourself !
Michael Dixon