Thats a bit vague though. You could say that if there is stopped or slower moving traffic in the left hand lane then then that would cover being blocked which would then allow you to go straight ahead (12 o'clock) using the right hand lane.
What problems do you foresee if traffic is going straight ahead using the right lane of a two way approach on a duel carriage way? Any cars in the left lane should be going left or straight ahead so as long as a car on the right lane going straight ahead also exist to the right lane then no problems there!
Interesting second point though. You seem to suggest that its OK to be in the incorrect lane going straight through because nobody else will/should/might be in the incorrect lane while turning right.
If everybody were to obey the current rules, local anomalies could or should be sorted out by local authorities.
Instead we have a situation where people decide which rules of the road they agree with and choose to obey.