It really isn't "tricky"! There should
not be any overtaking in this situation.
When turning left, you also have to anticipate that you may need to give way to anyone crossing the road, so even if a car could just about get away with clearing the junction before the cycle approaches, they still shouldn't be doing it, unless they are prepared to stop in a position that does not obstruct the cyclist.
Before overtaking you should make sure the road is sufficiently clear ahead
www.highwaycodeuk.co.uk
On my way home today (from a forum event), a car overtook me and immediately turned left. I had to brake suddenly to avoid a collision. This has happened to me on numerous occasions at this particular location alone.
There are sometimes a lot of words in your posts without really saying very much; I'm not prepared to read any further, as this really has annoyed me, especially given what happened to me today. Please think before you type.