Hi Ali
Fingers crossed that the house sale goes through smoothly and it’ll be plain sailing from there on in. 5 days turnaround for the visa is very good too, so it’s all happening for you now. I bet June will just fly by and you’ll be off.
I don’t think you can go wrong with the Asian airlines as they have a pretty good reputation. We’ve flown with both Thai Air and Malaysia Airlines. albeit was from here and not from the UK, but I guess the service would be the same. Thai Air was quite a bit cheaper for us than Malaysia Airlines {
long story ), but the service was about the same standard. Singapore Airlines seems to always be rated highly, too, so there’s a few you can choose from. We were lucky in that we had longish stopovers each time, which gave us a break in Bangkok and Kuala Lumpur, but I don’t know if you’d get the same breaks coming from the UK. I think we had between a minimum of 7 hours to 18 hours with our different flights/airlines and, because the airlines gave us hotels, we could shower, stretch our legs, do a quick sightseeing tour and have a night’s sleep (depending on the length of the stopover). We got back on the plane feeling fresher and never suffered from jet lag when we arrived in NZ. If there’s anything else you want to know about Thai or Malaysia Airlines, ask away. I know there's others on here who have used Singapore, so you might get lucky with some info on that one.
Meanwhile, I’ll drag out my favourite links again for you.

Check on
airline quality
Look for the
best seats.