After many days of reading all the forum posts and advice online about how to insure my car rental properly as a British driver in Maui, I thought I'd share what I've learnt for any other people struggling to make sense of it all. These are just things I've found this week, and maybe you'll find better deals, so always check!
1) Most UK car home insurance policies don't cover rentals in the USA, and if they do it's very basic.
2) If you buy insurance last minute when you're picking up your car, it will be ridiculously expensive. It can also be expensive if you buy it from the rental company in advance.
3) What you want is a 'Collision/Loss Damage Waiver' - this covers any damage to your rental car, and 'Supplimentary Liability Insurance' - this covers anything you (hopefully don't) hit!
4) If you buy it independently before you go, it is normally much cheaper. I found this website particularly helpful (moneysavingexpert.com/travel/cheap-car-hire). They recommend using moneymaxim to compare quotes, which I found useful. Even better, if you scroll down to section 4, there is a 15% off deal for direct-carexcess.co.uk which has offered me 8 days insurance including everything I was looking for, for £41. This is easily the cheapest I've seen by a long way.
Anyway, just a disclaimer that I haven't used any of these companies yet, so I can't recommend them, I just thought I would share the good deal and what I've learnt as this forum has been very useful for planning my trip and I wanted to give something back. Please correct me if I've made any mistakes in my research, or post if you've used this company and have any positives/negative experiences. I will post again upon my return!