Gold and Platinum are pretty much un-reachable. There are very few if any Platinum FVC members.
To reach gold you need to have booked at least 25 Virgin Holidays. Gold gives you a limo transfer to the airport and VS Flying Club Silver. Details
herePlatinum requires you to have been on a staggering 50+ Virgin Holidays [:0] and gives you not a lot more than gold except lounge access (I dont think it's Clubhouse access though) at the airport when flying on VS. Details
hereReally not worth trying to aim for gold or platinum as far as I'm concerned considering the huge amount of money you would have to spend to get very few real benefits out of it.
Regards