Sorry I will not be able to answer about the police letter but the rule in the round about is: If you want to take left Turn or U Turn, you should stay in the most left lane; If you want to go straight, stay in the middle and in the right lane for the right turn, you will never face any problem with the other cars.
The police normally imagine the touching area of the body of the cars if no body accept the fault:-
Like your car is touched in the rear half body and the other car's front half body is involved, then it is his fault. If your front half is involved with the rear half of the other car, then you are on the fault.
Anyway if you have full insurance, don't worry they will repair it for you.