I've never driven a LHD car in the UK or a RHD car in the US or Europe, but in general I'd say it is a bad idea .. the driver's view of the road is very restricted, very hard to pass, etc. In the UK, where many two-lane roads are quite narrow and twisty, how would you know how much clearance to give to a car travelling in the opposite direction (and, you could have a closing speed of 120 mph or more.) Sounds dangerous to me...
As someone who regularly drives a LHD car in Yorkshire, I beg that people with no experience please stop perpetuating this myth. In the past 18 months I have driven my LHD car as well as occasional RHD rentals (including a regular 60 mile round trip commute to Uni) and, in my experience, there have been more occasions where I have been happier in my LHD car - in particular on the two-lane, high speed roads cited here - because I can drive closer to the side of the road with confidence. To my knowledge I have never accidentally started driving in the wrong lane or gone around a roundabout in the wrong direction, etc because there are certainly plenty of other reminders and visual cues that keep me where I'm supposed to be.
Yes, it's a bummer that I can't see as easily around the farm equipment to pass on occasion, but overall other than custom I don't have any experience that would make me state unequivocally that RHD is absolutely better.
Also, I shipped my car here from the States, and I recommend doing the math before coming to a blanket conclusion that it's far more expensive to ship than buy here. In some cases it may be, but in my experience it was far cheaper to ship. YMMV. No pun intended.