It is a tough one. If they are about to remove lock down and you can be useful, I would say stay, although you don’t know what flights will be available in the future, and new waves of the virus in different countries may lessen the chance of flights so you may be there a very long time. I don’t know where you live in the UK but my experience is NOT that it is a shambles here. On the contrary. The hospitals local to us have lots of capacity, all specialities are still
open for business although many ops and routine testing on hold so that there are enough beds to make more intensive care wards. All respiratory staff are working flat out, but they have not been overwhelmed unlike in Italy / Spain, the peak was 8/10 April and now there is consistent high demand. If you are careful, you won’t get the virus. We are lucky, we get groceries delivered and have lovely countryside nearby, a garden and have had one of the most beautiful Springs I can remember, the birdsong without traffic noise is extraordinary. But social distancing will remain here, until a cure/vaccine, the virus is here and in the crowded island and cities, so we can’t hug a grandchild and may not be able to do so for another YEAR! So if you love hugs and can get them in NZ, I would stay.