Heathrow North Link to M4 road markings

[NadJ]

I work out of Heathrow. I usually join the M4 north link as depicted in red. Follow the red line as it turns left. Occasionally, I find that the driver in front of me decides to stop completely (especially at night) before he joins the other lanes. I can only imagine people do this because they think they're about to join a round about and MUST stop. But there's no stop or give way line. One might hasten to say they're being idiots but then cast your eye on the big green road layout sign, it doesn't exactly depict a merging left lane that has right of way.

On the other hand, occasionally, a driver from lane 2 on the "roundabout" decides to leap into lane 1 just as a car is merging on to the "roundabout" because he thinks he's going to miss his exit and because he expects the merging traffic to stop. This often results in a near-crash. I see it happen at least once a week.

Your thoughts?

[Mandat]

This is the view a few metres earlier, as you approach the roundabout.

The sign on the right (circled in red) tells anyone approaching everything that they need to know.

[InitialDave]

I think a contributory issue is the location, at a major airport. Disproportionate number of drivers who are only there very rarely, in an unfamiliar area. Higher chance of them not clocking a sign because they're a little lost or otherwise distracted.

[NadJ]

Mandat said:

This is the view a few metres earlier, as you approach the roundabout.

The sign on the right (circled in red) tells anyone approaching everything that they need to know.

Haha. That's funny. Never realised it.

Why is it on the right though? That's not conventional. Traffic is concentrating on turning left. Naturally a sign on the right doesn't register as well. Wouldn't a solid white line on the road be more appropriate here though?