Originally Posted by
Ldnn1
Welcome to the forum, hkstudent.
Yes, assuming this is for one person not two, you could apply it to the mixed cabin and it would be 19,500 + 39,000. You can book this online on avios.com
Note however that you may find it better value not to use the voucher for your outbound and instead just for the inbound - it'll cost more avios but will save you a good chunk of YQ. You'd have to call to make that booking though.
What this means is that you'd effectively be making two bookings.
So the outbound would be 39k + £250ish of APD and fuel surcharges, whereas the inbound would be 39k and only a few pounds of duty and surcharges. Booking both legs as one ticket would be £500 ish (figures made up from memory).