Firstly, really sorry it wasn’t your day.
The turn that went wrong is the infamous Burger King turn. The approach is a narrow lane (first set of alarm bells) with railings to the left (more alarm bells). There is a bollard on your right (yet more alarm bells) and it’s clearly a tight turn (final set of alarm bells!) With all this going on, the instinct needs to be to straddle the lanes. I suspect that, if the next lane had been clear, you might well have done this. But there was traffic there held by a red light whilst your left turn only lane was showing a green filter. So the temptation is to squeeze into the lane. Sadly, it’s virtually impossible to complete the turn from that position.
We all make mistakes. Hopefully you’ll get it next time.
Pete 