Thinking ahead, it sounds as though some service could be resumed by running Skegness services from the eastern bay platform, with access via the most eastern bridge. XC services would only be able to get as far as Beeston, London services could start from Beeston. Obviously the Newark/Worksop services would still be in limbo, and the Liverpool services too.
If there is an extended shutdown for Nottingham station, EMT, XC and Northern will need to do some mid-term diversions.
Matlock and Leicester EMT services run through to Beeston, and then up Lenton triangle and terminating in Bulwell, to connect to the Tram.
Another train shuttling Hucknall to Worksop on the Robin Hood Line. (connection between Bulwell and Hucknall by Tram)
XC Birmingham Trains, and EMT London stoppers terminating in Beeston, and turning in Beeston Sidings.
London Fasts Terminate at East Midlands Parkway.
Liverpool - Norwich divert down the Erewash Valley Line and calling additionally at East Midlands Parkway for connections.
Northern Leeds services terminate at Ilkeston (if possible).
Newark/Lincoln and Skegness out of the Eastern side platforms if allowed.
Rail Replacement buses: Nottingham to East Midlands Parkway, Beeston station to Beeston Tram, Ilkeston to Cinderhill Tram (assuming the Tram is able to run once the fire is out)
Would that work? I'm sure it can't be as simple as that, not least because of the problem of stock being trapped on the wrong side of the station.