It is strongly recommended that you create bootable Rescue disk - USB stick or ISO image (and burn CD/DVD disk) after you have encrypted your system or boot volume. In case of failure, you will boot your computer from the bootable rescue disk and run the rescue decryption process. Please note that it is a time-consuming process.
It is also recommended to create Windows Live CD with the BCVE plugin. In case of the failure, you can boot the computer from this Live CD and access your encrypted volume as a regular disk. You can mount it and access data or decrypt the volume.
Full overview of BCVE Rescue procedures is here: Rescue procedures