I see in one of your earlier posts you mention you hired a car....
I was thinking about doing this at some point in my trip, but don't know about the insurance/licence situation. I have a full UK licence, but am no longer insured on anything (I sold my car to put down the deposit).
I don't know if its different for me in the UK, but what was involved for you?
I rented a car twice when I was in Chile. The first time in Northern Chile and the second in Patagonia (I rented it in Chile and dropped it off in Argentina). It was pretty simple I just needed to show my USA drivers licence and a major credit card (Visa, mastercard, or Amex). I think I also had an International drivers license (here in the USA we can get one for $10 with a picture and showing our local driver's license, we usually get it at an Auto Club like AAA and it's good for a year).
The major companies rent cars down there so you could probably call a local branch in the UK and they'll tell you if you need an International drivers license or if your local one is enough (I usually get one anyway because it makes the local authorities happy when they see something in their own language. Not sure about the insurance situation but I believe that you are insured by the rental car company not you home policy, so I don't think it matters if you have Insurance at home.
I've also rented cars in New Zealand (twice), Namibia, drove one into the Ukraine, etc.. and suprisingly its always been pretty simple, just like renting one at home.
Just looked at your profile and saw that you are under 25 years old, that could be a problem. A lot of companies require that drivers renting their car be 25 years old. Just call a couple of the major companies and ask. Good luck!