The Scary World of Bleach

My very first home decor project in our current apartment was dealing with a very ugly couch.  You can read about my need for a cheap and quick slipcover here.  Our couch, after experimenting with sheets and draping methods looks like this currently:

Note that this is an old picture before we painted our end tables white.  The quick and cheap slipcover has held up for eight months and is still hiding the ugly couch like a pro.  The only complaint I have is the color of the sheets. When I visited Target to buy the flat sheets necessary for the project, they were out of the pretty oatmeal color I wanted so I purchased this green-tinted khaki color instead. In the picture it looks fine, but in real life it has more of a brownish-greenish tinge to it and I haven't been a fan since the day I stood in the Target aisle.

Now, why am I complaining about the color of our slip covered couch after living with it for eight months? I have a project in mind for the floor lamp (you can see it in the picture above) but I need to change the color of the slipcover for it all to really work.  The lamp project is still a secret for the time being, but I do need your help with the slip cover.  Ideally, I would like to find a way to simply tone down the darkness of the brown and lighten it up a little. In comes my idea of bleaching the slipcover. 

I've never really worked with bleach - I always seem to ruin things whenever I try to bleach out a stain so I'm a little frightened of the idea of bleaching the slipcover.  What do you think? Do you think it would lighten the fabric uniformly or do you think I'd get weird splotches of uneven color?