So I struggled a bit with the install and thought I'd post the steps for the benefit of others who might also be struggling.
1. As the C::B download page says, you need to get the wxWidgets packages from apt.wxwidgets.org. Instructions here:
http://wiki.wxpython.org/InstallingOnUbuntuOrDebian. Step 1 is optional, steps 2 & 3 are essential.
2. Following 'apt-get update' (step 3, above), run:
> sudo apt-get install libgtk2.0-dev
> sudo apt-get install libcodeblocks0
> sudo apt-get install codeblocks
Easy as that.
Cheers!