Barbel on the Nymph

Hey guys, I want to target (european) barbel soon on the fly.

I was told that a squirmy wormy or sth. bushy (like hares ear) would be my best bet.

I got two questions:

1. What‘s the best colour for squirmy wormies? (Got white at home, will it work?)

2. I saw some dudes from London kind of Euro Nymph for them with enormus beads (I bet they were like 5,5mm tungsten or bigger).

Makes sense to me to get those nymphs down. Since I do not own beads that heavy, would sticking two beads on a bigger hook work too?

Thanks in advance, tight lines!

PS: Pic with a barbel I caught a few years ago on the fly rod.