Don't get me started on signals, one of my pet hates. I fail more people on driving assessments and on advanced test for giving the wrong signals at the wrong time with the wrong meaning than just about anything else, and I have lost count of the number of crashes I have dealt with, again because of improper signalling, and I am not talking about failing to give a signal but giving wrong signals.
Its what we call in the trade as lazy driving because most drivers do it on automatic pilot as a result of what they have been taught to get their licence resulting in them driving by numbers rather than reading the road, planning and then considering the appropriate course of action to take which does not always require a signal to be given, or, a signal being given in a different part on the road to avoid causing confusion to other road users, and this can include carrying out U turns.
I know what signals mean -
Left winkers mean, 'I just pulled in front of you'
and Right winker means, 'I have overtaken you'😏
As to the original question; some of the replies have suggested signal right and off you go.
But a U turn is abnormal behaviour, putting everyone at risk, or that's was I was taught.
It is always better, to turn off into a quiet minor road, (on the right) do the turn round in there, and then re join the major road as a left turn.
Or wait until the next roundabout.
Or stop on the left, wait for the traffic to clear enough for you to turn without impeding anyone else.
Looking at the picture, the road markings suggested a hazard behind, and similarly there is a hazard ahead so (in my book) not a good place to be doing a U turn.