Can't offer a place I'm afraid, but maybe some random advice...
Stansteads in a bit of a mad place when you're passing through. We were there for 6 hours on saterday on the way home and went to a place called Bishop - Stortford (

) or something which is only a few mins from stanstead if you're stuck it's close anyway.
If you end up heading for London city, I'd recommend the bus. It's only a fiver conpared to twenty something of the train and only takes 20 mins longer.
I'm sure someone'll be able to help though...