I'm a righty but managed to drive a stick-shift in Ireland without too much difficulty. I wonder if it actually helped that everything was on the "wrong" side (driver's seat and steering wheel, stick shift, traffic direction) -- bc I was forced to remain focused and deliberate about everything at all times. That said, navigating my first few roundabouts I found myself verbalizing the flow and my intentions, to suppress my instincts and merge smoothly. (Tangent: speaking thoughts out loud is a useful hack in many situations!)