I have a similar problem to the OP on my route which I have to do twice a day as per the map here:
My understanding is that I can go in the RH lane around the roundabout and then indicate left at Point B then move across to the left hand lane of the exit road. This means that I am in the left hand lane of the carriageway when I get to the side turning, all happy following the red dots.
The problem as you will no doubt have guessed is that traffic exiting from Point C, that is to say turning left and going in the same direction as me, always assume I will stay in the right hand carriageway and pull out regardless of where I am on the roundabout blocking my movement across to the left lane. My understanding is that they are in the wrong as they are not giving way to traffic on the roundabout but many people I speak to disagree with me.
If I do stay on the right and let them pull out and I follow the green dots, more often than not I end up having to try to pull in behind them but with high volumes of traffic this is not easy especially as I will be braking shortly to turn left. In addition there is a pedestrian crossing before my side road turning just after Point D which makes this manoeuvre even harder if someone stops the traffic.
The other alternative is to accelerate fast and cut in front of every one but this is dangerous and I have to brake hard at the side road. I should point out that I have a 1997 Punto 1.2 as a winter hack so everyone on the road can out-accelerate and out-brake me…..
I am at the end of my tether with this now. The worst case scenario is if I want to go into the garage at Point E as this is directly off the exit so you have to move across very early. Bear in mind also that people coming on to the roundabout from the west also seem reluctant to wait!
There is an alternative – I can go to the next roundabout and approach this one from the west so that I am nice and safe on the left all the way but on principle this annoys me and it also adds more time to my journey especially in the evening rush hour.
Any advice??!!