Unfortunately, Melton Mowbray airfield itself is closed. Sad loss to mankind.
There are a few that might be of interest:
Leicester (maybe a bit far away)
Langham (Private - need PPR etc)
Saltby (but that's really gliders only)
Cottesmore (OK with PPR)
Exton (Private again)
I don't know if the private ones are still open - nothing promulgates closure of a private airfield.