Re: Max fine
"a 0.4% of turnover fine could actually scare the board."
Depends. If it's paid from company funds, it'll be a while before company behaviour changes.
If the penalty was payable by the individuals on the board (same way as megabonuses are payable to the individuals on the board) they might start to think about changing the way they do business.
Strangely enough, the ICO has recently been talking about similar kinds of thing (e.g. companies going bust rather than paying a corporate penalty).