Jolly good - that was the answer I was hoping for

Off to ANU in 10 days, after which I should have the full 80K. My partner will have a shade over 60K, as soon as her Virgin mastercard comes through. Looking to go LHR-LAX in mid-october, so it should be one UC full monty for me and one economy to UC upgrade for my Long Suffering. How do we go about booking these flights? I notice from the VS Terms & Conditions that upgrade tickets can be quite limited as far as dates and availability are concerned. Howcan we make sure we get what we want when we want it? Wouldn't want to rely on hoping for an upgrade on the day, for instance.