Thanks all for your replies. It seems the consensus is that 2 tickets is not worth it. Given that flying BA to NZ with the companion voucher is not possible, I think realistically we are left with the following options:
1 - One way avios ticket on Qatar, Cathay, Malaysian etc., London to Auckland. The reality is this will likely cost more than 300K avios (for 2 adults + infant) in any of the premium cabins, given 2 sectors. As pointed out above earning/purchasing additional avios could make sense depending on amount and cost.
2 - One way cash booking on similar. I am not sure any airlines offer one way tickets on this route for any less than approximately 80% of a return (sometimes more than the return), particularly in premium cabins.
Is it possible to book a single ticket on these airlines in different classes (for either avios or cash)? For example London - Doha leg in Economy, then Doha - Auckland leg in Business?
Also I take it there is no option to upgrade using Avios on non BA flights? (Edit: I have seen that this is not possible except on certain American/Iberian flights, which don’t help get us there either).
Last edited by Colossus; Feb 21, 2021 at 1:07 am