Here are a few thoughts about driving in England, from an American perspective.
This is besides the left-side driving (I’d repeat the mantra “Driver in the middle, driver in the middle”) or roundabouts (simple once you know some rules such as “the one in the roundabout has the right-of-way”).
The thing to be cognizant of is that most roads were set in place before the invention of the automobile.
Don’t get me wrong; after a couple of days practicing in Suffolk, I was relatively comfortable behind the wheel, so long as I skirted the towns. By the time we’d made our way across the country to Cornwall, I was playing the theme to All Creatures Great and Small on my phone and in my head while driving through this green, pastoral countryside.
The largest roads, the motorways (Designated with M- just like our interstates are I-) are typically divided highways, with 2 lands each. Unlike interstates, shoulders are not a given. There may be periodic pull-offs, but much of the roadside is tall weeds or rocks.

The next roads (often with the A- prefix) are like our 2-lane roads, again excepting the lack of shoulders. Hedgerows, banks, and walls are common, and pull-offs are infrequent. The listed speeds are 50 or 60 unless near towns, but I rarely felt comfortable going that fast. The roads seldom have long straight and level stretches, so passing isn’t something I practiced a lot.

But wait, it gets more interesting. Farther in the countryside (and some village streets) are what I called 1 ½-lane roads. Same obstacles on the sides, but meeting an oncoming car leaves no room for error. The two vehicles creep past each other, left mirror brushing weeds, right mirrors not quite touching. In villages, parking takes up most of a lane, so opposing drivers have to decide who yields.

Then there are the tracks that, while paved, are meant for 2 horses abreast or one modern car. If you see headlights, either find a pullout (which may be just deep enough for your passenger wheels) or back up.
One things to remember on anything less than an M road: travel will invariably take longer than you expect. In my home county, I can cross 17 miles of rural road in around 20 minutes. Along the winding tracks of rural England, a 3 mile drive took over 10 minutes; another 5 mile distance, 20! Folks used to rapid mobility will need to recalculate their travel estimations.
I negotiated the roads without major incident, owing in part to the fact that the drivers around me tended to be more polite, and forgiving, than I had a right to expect.
