In friend's car, set out for a longish trek from Stoke Newington --> [don't recalll locale], but it was at night and I managed the maybe 10 mi run without killing anything/or dying. Later w/car's owner along, I lost-REFS at a roundabout; did the prudent thing of going with the flow at that point--not in correct direction. It got sorted, shortly. Point: both events needed 99% concentration ... I'd never pass the onerous UK driving test.. without X mos of 'creating/reinforcing' the new habits.

(My first experience--in the A-H Sprite in '60)--found self on the wrong side of a dual carriageway--fortunately or unfortunately empty! Had there been one other occupant it would have been instantly obvious this was Rong, of course. A luckily-nice Bobby stuck out a hand from roadside, saw I was a new-Yank and sent me to make it So, sans handcuffs. No problem later from Londinium to Harwich ferry, nor a few months later: from Channel ferry to Birmingham(?), thence ferry to Isle of Man.

tl;dr: I don't think this switch gets easier as geezer-hood looms; guess I'd say, "think twice" at least, before guessing.. just how quickly-AND-perfectly? you would perform. 46 yrs is a long gap in assessing one's adaptability, I wot. fwiw