Buying a 2015 Nissan Leaf - which iOS apps to use?

Hi,
I'm buying a second hand 2015 Nissan Leaf 80kW Acenta 24kWh in the UK. I'm confused about which iOS app is best to use to communicate with it. There seem to be several, with pretty terrible reviews online. I would like to be able to remotely view the charging status, and ideally set climate controls on a timer etc. I also can't figure out how I'm supposed to register as a new user with the app. Do I do it in a web browser online? Which of the many Nissan portals is actually linked to their iOS app?
Many thanks
BC

I would like confirmation on the above questions too, except relating to a 2017 leaf which I’ve picked up today.
Tried to use the Nissan connect app to pair with the car, except the menu option it asked me to select in car don’t exist.
Tried searching the forum and didn’t find what I was after, so if I’ve missed it, apologies.

In the US, the Nissan website includes NissanConnect: www.nissanusa.com/Connect/, but I see that the iOS app has a low user rating.