Good luck with that is my first thought!
My experience redeeming miles with Virgin was extremely painful as they have one of the most difficult to redeem mileage policies in the air.
Last year I had 120k to use up with the idea that I could buy a couple of premium economy tickets and then upgrade to upper class with miles. Turned out that:
a) You need a certain class premium economy tickets to be eligible for an upgrade (normally more expensive than discounted upper class anyway)
b) There is never more than one seat available on whatever flight you are trying to redeem against no matter when you are travelling.
The conclusion I reached was it is best not to try and upgrade with miles but redeem against a free flight and pay the tax instead. Even then you will struggle on the popular routes.
In the end I managed to get a free upper class flight to Vancouver as it was shortly after they launched that route so availability was good. The only other place that I could get was Capetown.
Another point which you have already seemed to cotton on to is to speak directly with the upper class flying club as they are considerably more helpful than trying to find a flight on the website.
Since redeeming my miles I’ve shredded the flying club card as it’s pretty useless and changed airlines.