Nottingham dominates Nottinghamshire more than most English cities dominate their counties, and that shapes everything. A large share of county search resolves to the city, and businesses in the north of the county are frequently invisible as a result.
The north of the county is a separate market
Mansfield, Worksop, Retford and Newark form a tier of towns with their own economies and very little commercial overlap with Nottingham. The former coalfield areas around Mansfield and Ashfield in particular have distinct demographics and a business base that serves locally rather than reaching into the city.
A business in Mansfield marketing itself as Nottinghamshire competes against every Nottingham firm and wins nothing. Naming Mansfield wins locally, where there is barely any competition at all.
Newark is oriented elsewhere
Newark sits on the A1 and the East Coast Main Line and looks toward Lincoln and Grantham as much as toward Nottingham. Businesses there frequently serve a catchment crossing into Lincolnshire, which is worth saying explicitly rather than leaving the boundary ambiguous.
Student demand moves the calendar
Nottingham has two universities and a very large student population, which shifts demand in housing, food, transport and services sharply around term dates. Businesses serving that market should plan content and campaigns around the academic year rather than the calendar one.
Where the opportunity is
Nottingham itself is moderately contested and worth the effort if you are in the city. Everywhere else in the county is lightly contested, and the fundamentals alone will usually put a business ahead of its local competition.