I would boost the luminosity and contrast on the arch and big boulder at the right by PS to complement (but not equal) those on the left rock surface.
I wonder if another composition, or two, can dramatically improve this image. E.g. one that shows some significant details of the foreground rocks for better scale, or another that shows the arch's hole against the sky for better contrast, or a combination of both. I would be tempted to get very close to the left big rocks and on my knees/belly for such a combination. Or, yet another that shows more of the water with reflected sky colors/clouds. Under such great lighting and clouds, I would have shot quite a few frames, including some after the sun sets.
Another vote for posting comment requests at the critique forum.
After two weeks in Northern Ireland I don't want to keep back the results from you.
If this picture goes down well in here I'd like to upload some more in next few days, if nobody minds though.
Comments, criticism, improvement suggestens are welcome.