Restarting exercising following a broken ankle

I've still got 17 days in plaster cast before it comes off and I'm hopefully signed off from the orthopod consultant. The week following cast removal I am due to go on a city break which is going to be a fair bit of strain on my newly healed ankle. What can I do to offer my ankle support following cast removal and more importantly, when I can start recommencing the 3-4hrs high paced (Body Combat mainly) exercise I had been doing prior to my injury...I need to get a move on with my weightloss again!!