Originally Posted by danmushman

ok makes sense you want to keep/achieve silver before the NZ trip then, for priority check in / lounge / seat selection etc.
Check prices for LON-SOF trips in CE.
It would probably be better for you to not make silver before 8 Nov, then after that book 3 trips to get 480 TPs.
As above, that way you'll be silver for another 24+ months. If you do your 2 trips before 8th November you'll only get it for 12+ months. (If you think you'll comfortable make silver anyway with NZ + other trips then don't worry too much).
If you book 2 bookings 'nested' - LHR-SOF-LHR & SOF-LHR-SOF on two dates you can get away with doing B2Bs so only 2 days of travel in total and minimal time at SOF. There's a lot of detail in other thread re this.