I am new to driving but still think I was not in the wrong. If I am can someone explain why thanks. I have attached a diagram to explain. I am the blue car and the blue line shows the path I am taking. I was using my indicators. The orange car is the other car in questions and the orange line is the path they deciced to take. They did not indicate and I did not know they wanted to change lane on roundabout until I got on. When I got onto roundabout (the outer lane) the car decided to change to my lane (see the orange line going from inner lane to outer lane) then pip their horn and then speed past me after both exiting roundabout and give me the middle finger. I am wrong to have got into the lane indicated in diagram (the outer lane) on roundabout when that lane was clear and only the inner lane had a car in it. Thanks sorry if not clear.