Outside of London, never mistake a lot of cars as a traffic jam. It will most definately be a queue and, to avoid embarrassment, you should get in it as soon as it is possible.
We are on a dual carriageway and at the end is a roundabout where most of us want to turn right.

If we were on the continent, both lanes would be filled with cars trying to nudge into the right lane just before or even on the roundabout.
Luckily, we’re not on the continent, this is England.
As soon as you realise you are not in the lane that you should be, you must instantly stop and indicate.

Then slowly and apologetically, for you are a queue jumper, you must nudge your way in, and once in you must either wave thank you to the driver who has just let you in or flash your hazards to show your appreciation.

It is much more of a social taboo to queue jump than it is to hold up traffic, and it is this queue jumping taboo that keeps us from doing it closer to the roundabout. Because if we did, people would tut.
