There is a P&O Cabins page on Facebook with tons of info about rooms..

Have a look at deck plans on the P&O website and when you see one in a position you think is okay put the cabin number into Google and with a bit of luck you should see photos. Don't forget to check what is on the deck both immediately above and below your cabin.

I'm not sure about a cabin with a bath. They do exist but I think I'm right in saying they are only in the expensive cabins.