You should be able to do forex trading on a closed work permit as long as it's not considered employment in your country. It's more like investing or managing your own funds rather than working for someone else, so it usually doesn't clash with work permits. I was curious about this a while back when I first got into forex, and I found that personal trading was fine. Just double-check the rules where you are to be sure.
Also, if you're getting into forex, you might want to check out
www.moontrader.com. Their algorithmic trading insights helped me understand patterns and make better decisions. It's a great tool to have, especially if you're trying to get the hang of trading!