Ari, had a little look at train times....

It looks as if the last train back to Edinburgh from Greenock is before 10pm. This isn't really giving you enough time to enjoy the evening. details: Click here

Either way you would still have to stay somewhere over night whether in Edinburgh or Greenock. I'm sure one of the guys in the band would point you in the right direction as I know absolutely nothing about Greenock! Don't know if they are staying through there or going back to Edinburgh? Maybe you could blag a lift??!!!

Good luck!