A while back I rebuilt my laptop to use Windows 2008 Server.   The main reason that I did it was so I could develop SharePoint applications on it rather than having to use a VM.    At the time, I forgot to partition my hard drive so I could take advantage of BitLocker.   Anyway, not to long ago the time can when I realised that I need to re-enable BitLocker.   I thought that I was going to have to rebuild it.   However, I spent 5 minutes searching the web and came across the BitLocker Drive Preparation Tool  this tool does the following for you:

The BitLocker Drive Preparation Tool automates the following processes to make the computer ready for BitLocker:

•Creating the second volume that BitLocker requires

•Migrating the boot files to the new volume

•Making the volume an active volume

Once you have run the installation program a new utility called the BitLocker Drive Preparation Tool appears on you menus and once you have run it, rebooted a couple of times it allows you to enable BitLocker.