Significantly more than one with a manual transmission. However, I assure you that if you follow my advice, you will come back to this article to thank me.
The drive on the left , especially in the first kilometers, requires a lot of concentration . Having the automatic transmission allows you to:
forget about your left leg and therefore no friction
do not use the gearbox
not needing to hear engine revolutions
do not “rub” and / or have the machine turn off at an intersection
This last point seems to be the antithesis of the expert driver. However, imagine yourself at a stop. You need to get in there, you have to think which way to really fit in (and already here you use almost all the available reasoning capacity of the brain), to risk playing badly with your feet and having a drop in pilot performance, is a moment.
Joking aside: the automatic transmission allows you to halve the things you need to think about and concentrate on all those mechanisms that are automatic in right-hand driving, while with left-hand driving you have to think about it.
Once you have left very calmly, if you have rented a car, you will have to take measures. The first kilometers are important because you will exit the rental (potentially that of the airports) and you will enter roads that are certainly not country roads. You will find a few cars, so the first kilometers go flat and discover this new world of left-hand driving.
From my experience, I believe that it takes about 200 km to become aware of the vehicle and the new rules. My experience, however, is the result of driving on the left with a rented car, which means that the driver is on the right. I never happened to drive in my personal car.