Woks aren't really designed to be used on UK cookers, in the far east and in restaurants/takeaways you have big ring burners, with a much bigger gas supply. It's also easier to toss a wok using a proper wok hob, as they normally sit in a hole, so you can use the edge of a hole to flip things up.
You can stop the juices coming out of the chicken by "velveting" it (google it, it's the standard Cantonese method, but it's basically coating it in egg white and corn flour) it seals the meat, and keeps it juicy as well as acting as a barrier. The other method is just putting the meat in a deep fat fryer for a few seconds before putting in the wok.