I swear there's a thread about this somewhere, but for the life of me, I can't get the search terms right to track it down. I just booked a rental car for a trip where I'll be in Scotland next summer. I've never driven in an LHT country before, the only countries I've driven in internationally being Canada, Iceland, and the Philippines. Anything stick out for anyone that has driven in the UK or elsewhere that is beyond "you just have to get used to it"?
I have driven in the UK and Ireland in vehicles equipped with automatics (center-column shifters in all cases). I'd say the transition from RHT in LHD (North America) to LHT in RHD (British Isles) is pretty easy for an alert and attentive driver, so far as vehicles are concerned. The more difficult adjustments have to do with signing and typical streetscapes. There are some technicalities to signing, especially in the UK, that are not intuitive to Americans (e.g., speed limits based on lamp column spacing, or different types of 20 limits such that you see signs saying "End 20 zone. Speed limit 20"). And although engineering standards for unit lane width and so on are very similar to those used in the US, streets and roads are just narrower in general, so you have to be much more alert to the need to alternate with oncoming vehicles. About 99% of the public road mileage in the UK is paved for dust suppression, but the proportion that has been engineered in the modern sense is much smaller.
Scotland in particular used to be full of long-distance single-lane A-roads, especially in the Highlands. I think some of them may even have had primary route status.
It is quite common for rural roads to have turf dikes at their edges. Roads so equipped tend also to have narrow ditches on either side that begin about a foot behind the edge and are hidden by vegetation. You don't want to pull off (e.g., to take a picture) and have one of the wheels drop into the ditch. The underside of the car will then be beached on the verge, and though it likely won't be damaged, you will need help to get all four wheels back on terra firma.
The traffic engineering community in the UK does not believe in advisory speed signing for curves. (The methods we use in the US, such as the ball bank test, are not considered reliable.) Thus, while there is a prescribed sign for advisory speeds, it is used far less frequently than in the US. Driving on rural single carriageways that have not been developed to WS2 standards (similar to Super Twos in the US) is thus a bit like driving in Montana, where MDT is similarly sparing with advisory speed signing.
I recommend reviewing the
Highway Code and
Know Your Traffic Signs before you go.
I haven't personally driven a RHD vehicle before, but I've heard it's really easy to reach for the turn signal and (a) there's no stalk there at all or (b) you turn on the windshield wipers instead.
This has never been an issue for me in the UK. I recall (and a check of current Vauxhall ad copy seems to confirm) that controls for the turn signals and wipers are on the same sides of the steering column as in the US. There are other LHT/RHD jurisdictions where they are reversed.
I think the only tricky parts were: remembering that left turn movements are easier, and now right turns are the one which require a little concentration. That, and getting back into the vehicle on the correct side...
When I was driving, I really struggled to remember to go for what would be the passenger side in the US.
On a more serious and safety-critical note, I found turns out of driveways into single-carriageway roads were dangerous, especially when recently arrived from a country with a different circulation rule. On my first day driving in the UK, I made the same mistake
Anne Sacoolas did--I turned right out of a driveway into the right lane--though I self-corrected in fairly quick order.