It is worth saying at the outset that Electoral Registers are not compiled at the county level, but at the constituency level. That said, the Nottinghamshire Archives in Nottingham definitely hold copies of all the registers from 1945 to 1948 (as KGarrad has said, there were no Registers during WW2) and no doubt also hold them from 1948 to 1959. If by any chance you are interested in the Newark Division, Newark library also holds copies for that area for 1920-1939 and 1946-48. This information is based on the reference book Electoral Registers 1832 -1948 and Burgess Rolls by Jeremy Gibson published by the Family History Partnership 2008.
As you may be aware, the Representation of the People Act 1948 changed a number of things concerning both the franchise and also how parliamentary seats were organised. In particular Nottinghamshire went up from 9 MPs to 10.
