Stopping or slowing down at the edge of the road

Check in your mirror to make sure you can slow down and stop safely.
Signal your intention to change course and pull in.
Signal your intention to slow down either through the brake lights or by moving your right arm up and down outside your vehicle window (shown below) if you think your brake lights might not be working.
Use a traffic lay-by if one is provided or pull in and stop close to the lefthand edge of the road.