How about:
* Castle Donington Derby (the original IATA code was CDD for this very reason)
* Diseworth International Airport
* Islay Walton Airport
* Birmingham Northeast (probably the option Ryanair would favour!!!)
* Brian Clough International (could be appropriate given he was a manager at more than on club in the region)
Alternatively, just leave it as Nottingham East Midlands as it does convey an indication of where the region actually is, which to my niave mind does seem vaguely important.
Andy