If you drive on the correct side of the road like people in Ireland and a few other enlightened countries do, the outside lane is the right hand lane. The rest of the world bizarrely drives on the other side so they should avoid the left lane. 😉
As the AA says, there’s no such thing as the “fast lane”.
There’s no such thing as a ‘fast lane’ on a motorway. Traffic should always cruise in the left hand lane. The right hand lane is for overtaking other vehicles; it’s also used when approaching a slip road in order to let traffic join the motorway from the left. On a three-lane or multi-lane motorway the same rules apply. Keep to the left as much as possible. Traffic should never be in the right-hand lane on motorways if the left hand lane is clear.