"Never having "upgraded" from WHY to WT+ before (only ever paid for W or T class tickets), how do I go about it?? Is it done before ticketing, or done at the airport?? QF does not codeshare on this flight (or so I was told by Premium Desk CSA who I spoke to)."
There are a few fare types ( such as the OW RTW tickets) which allow a purchase to upgrade from 3rd World Traveller to WT+ (T) in advance for a fee. Normally it is a full fare recalculation though. You can purchase WT+ upgrades on the plane as long as there are seats available for £200 per sector which are a pretty decent deal. Check in the lounge whether WT+ is full before heading off to the aircraft just speak to the CSD as you board the aircraft and request to purchase an on-board upgrade to WT+
Dave