As someone who had to deal with a boss who wanted to "try" driving in the UK, here's my tip: make sure someone else is in the left-hand front seat to navigate for you. My boss didn't have any problems handling operating the car, but navigation is difficult if you're spending all your time watching the road. Also, be careful going out after dark until you're comfortable. We found that after-dark driving is more difficult trying to read road signs and so forth.