It's sounds like a really hard water you are targeting, But when they come on the feed they are stunning fish judging from your photo's from previous catch.
Better luck next week mate.
I'm going myself on Monday its also a hard water where I'm going and I'm from up north so I'm going with no great expectations. If I manage to snare one it will be a bonus and they are also stunning fish really dark almost black. I just can't wait to get out on the bank I don't get too go very often.