No idea about Virgin, but if you're parking at Gatwick I strongly recommend you park it yourself and hang on to the keys. I've heard too many stories of cars parked in fields and being driven like they're stolen to let some unknown loose in my motor.
The long term parking is an easy enough bus ride to the terminal (personally I always park at the South Terminal, regardless of which one I'm flying from), and if you book early enough you can get good savings on the short stay and walk from there.
Cheers,
Plug