| I've got both a LHD new MINI and a RHD classic Mini in my garage, and I've also driven quite a bit in the UK so I am very used to switching back and forth. As others have said above, it is very easy and natural to do.
The only thing that is completely weird to me is driving an older RHD car that still has the turn signal lever at the 3 o'clock position. Apparently, some time in the late 1970's and early 1980's most car manufacturers began building only one kind of steering column for both LHD and RHD cars they made: one that had the turn signal lever at 9 o'clock. Must have made manufacturing sense to just make one part, and it seems most of the RHD world has adapted over time. When I restored my classic 1965 Mini about 6 years ago, I kept it as RHD (would have been easy enough to switch to LHD had I want to do so), but I made sure I changed the turn signal from the 3 to 9 o'clock positions to keep my sanity intact.
+ 2002 MINI Cooper S - Dark Silver / White roof, Sport, Premium, Lapis blue leather
+ 1965 Mini Traveller - Tartan Red / White roof, 1275, Cooper S discs, fully restored/renewed | 
