What should a driver do when they want to safely change to the lane on the right in which there is other traffic?

Move gradually into the right-hand lane, indicate and then check mirrors.
Pull in and stop, wait until a suitable gap appears and then move out to the right-hand lane.
Increase speed until travelling at the same speed as the traffic in the right lane, then move over and check mirrors.
Use the mirror, signal and move into the right-hand lane when a suitable gap appears in the traffic in that lane.

Explantion: Any time you change lanes, you should use the Mirror–Signal–Mirror (blind spots)–Manoeuvre routine. Check your mirrors, signal your intention, check your mirrors again (and your blind spots), and when a suitable gap becomes available manoeuvre the vehicle into the next lane, giving way to traffic already in that lane.

Theory Tester

What should a driver do when they want to safely change to the lane on the right in which there is other traffic?

Managing Risk