Leather needs to be warm to be conditioned, otherwise the conditioner is not absorbed. A hairdryer can be used to warm it up, however it is hard to maintain a warm temperature within the cabin to allow for absorption.
A good way in doing this is putting heaters in a garage to get the air temperature up. However this can be costly to do, I wait for a sunny day when the temp is reasonable and get on it around 12 so the temperature in the car is warm.
Leather doesn't need to be warm to clean or protect it, however if your cleaning it first it's best to wait till the leather is dry before applying a protection cream, obviously the leather will take a bit longer to dry when it's cold as appose to when it's warm.
Most leather used it cars is a pigmented leather with a clear coat finish, meaning the leather is not absorbent and a conditioner will not penetrate through the clear coat therefore you are not conditioning anything.
It is important to protect the clear coat by keeping it hydrated as when allowed to dry out it will start to crack and split, leaving the colour exposed which will eventually come off. So too sum up your better of using a protector rather that a conditioner and as the leather is non absorbent it doesn't matter if it's warm or cold when you protect it.
The polish isnt anything flash, Meg's clear coat i think. Was going to remove tar with petrol, clay bar and then the Meg's.
As for the conditioner, I've got Liquid Leather cleaner and conditioner, smells nice