On the north side of my house, there is mature English ivy (6 or 7 years old) growing well in a 6 by 25 foot area. How can I get rid of the ivy and prep the area for planting? (I need more space for perennials!) I would rather not use herbicides, but pulling up all that ivy would be really tough. Any suggestions?

Unfortunately, English ivy is a very tough plant to remove without the use of an herbicide. As you stated in your question, pulling up all the English ivy is going to be difficult at best. Not only is it tough to physically remove the vine, it is going to be even tougher to remove all of the roots from under the ground. This plant can sprout back up from roots that are left in the ground, so it is very important to remove everything, which is not an easy task! English ivy is even hard to get rid of with your “average” herbicide. It is recommended to use a more powerful herbicide such as Bonide Poison Oak & Ivy Killer in accordance with the directions on the bottle.
With a plant as tough to remove as English ivy, the only real alternative is to use an herbicide. I hope this does not deter you from making more space for your perennials!