Oooh, that's really quite a substantial misrepresentation of what is actually in that link about the HGV veering from one lane to another.
The speed of a vehicle in front should not be an issue to any driver:
Stopping Distances. Drive at a speed that will allow you to stop well within the distance you can see to be clear. You should
- leave enough space between you and the vehicle in front so that you can pull up safely if it suddenly slows down or stops. The safe rule is never to get closer than the overall stopping distance (see Typical Stopping Distances PDF below)
- allow at least a two-second gap between you and the vehicle in front on roads carrying faster-moving traffic and in tunnels where visibility is reduced. The gap should be at least doubled on wet roads and increased still further on icy roads
- remember, large vehicles and motorcycles need a greater distance to stop. If driving a large vehicle in a tunnel, you should allow a four-second gap between you and the vehicle in front