The rule here is short but often broken: don't push into an intersection or crossing you can't clear. Blocking it helps no one and is an offence.
Don't block what you can't clear
In a traffic queue approaching an intersection, railway level crossing, pedestrian crossing, or an area controlled by pedestrian signals, don't enter or try to cross unless there's room for your vehicle on the other side. Stopping in the middle blocks cross traffic and pedestrians.
The one exception: turning right at lights
When you're turning right at traffic lights and no other cars are already waiting to turn right, you may move into the intersection and stop there, completing the turn when it's safe — even if the light has changed from green.