Patience, a bit at a time and by the Spring it will all be done. It may look a daunting job, but its never as bad as it seems. Cut it back first and then prise the ivy off the wall a bit at a time - dont be greedy!! If it is an old wall however, it may be better to trim it up and leave it. We have encountered some sites where the ivy is virtually holding the wall up and its removal would mean a pricey rebuild.
The good news is that It will be virtually dormant between now and April so you will not need to worry about the growth overtaking you!