I managed pretty well in Ireland a number of years ago when we drove the Ring of Kerry, staying in B&Bs along the way. The roundabouts were the hardest, especially at first, and it took conscious effort to "look the correct way" at intersections. I also managed to survive similar in Bermuda a couple of times on rental bikes. As long as you pay attention and think before you do, you should get reasonably comfortable pretty quickly.
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The most expensive tool is the one you buy "cheaply" and often...