Thanks for all the replies, not that many of them actually addressed my query ;-)   It's certainly not my plan to mess with Garda!

I'm aware that when driving on the left (as I'll be in Ireland) my question would refer to a right turn, and that roundabouts void the issue. MudGuard says that Germany now uses the American system, and McGrath seems to say that in the UK you can take your pick (that's a bit scary, innit?) Still not sure what they do in Ireland and Italy.

MudGuard -- we'll be driving from Hamburg southwest toward the Rhine with a sidetrip to the Mosel, then south to Freiburg, where we'll drop off the car and take a train to Milan.

Cheers,
Michael