I did one similar back in 2013, see my signature below. It was a one-off out of Copenhagen, so don't know if they do it any more, I'll see if I can find anything. One of the better cruises I've done. Can't remember the exact stops, but I know we did Cobh, Inverness, Dover and at least two more. I know we did tours of Loch Ness and the Guiness Museum, so whatever ports might be close to there.
Update: RC has a spot for British Isle cruises on the website, but there is nothing there. I can't post the link, but it's <rc website>/british-isles-cruises