Well, since your disk is damaged, you'll probably want to get a new one to replace it, yes?
When you order your new drive, get a USB (3.0, if supported) adapter to go with it. Then, when they arrive, mount your new drive via the USB adapter and install a bootable OS X system on it. Make sure to partition it as a 'GUID partition table'. Also, leave yourself enough room for your extra partition(s) at this time.
Once you can boot from it, you could backup your existing HDD to it, then swap the new one into your macbook.
Alternatively, you could just get the new drive bootable and then install it, using the USB adapter with your old drive to retrieve your data.
Also, you should be able to get a copy of the OS X installation program from the App store.
You might also try to press and hold the key during boot -- immediately after the boot tone and before the grey screen. This should present you with a choice of bootable images. One of them should be a recovery partition that was created when the OS was initially installed. That might allow you to attempt to repair your HDD. This is also the mechanism you'll use to boot from your new external disk when you install OS X to it.