The CPL is generally quite a simple test, and pretty much identical to the PPL. There is a little more instrument flying in it, and they expect you to fly in a professional manor (i.e trying to save money etc and show 'commercial' sense but obviously not to the detriment of safety)
The actual route isn't that much longer as I recall, like I said its a pretty similar test! look at the standard document for the CPL and it will explain exactly what the examiner is looking for.
now the IR on the other hand....