I'm 300 miles away so this isn't exactly local advice, but I'd recommend Leighton Moss RSPB. There are certainly Bitterns and Reed Warblers there, I don't know about the other birds on your list. As a bonus you would have a good chance of Avocet, Bearded Tit, Marsh Harrier and perhaps Water Rail. I would also recommend the cakes in the tea room