Take a look at my case (link below, page 4 and 6), there are several abuse of process arguments (which are skeleton defence arguments as well) in there.
The reference to Hatton is Hatton itself. Make sure to have plenty of copies with you.
The defence to either charge is more or less the same. All of that is set out in my case below as well. Read the Code for Crown Prosecutors, it states that the CPS must have "enough evidence to ensure a realistic prospect of conviction".
To have enough evidence for the speeding they have to have your identity, which would be supplied by the NIP. They don't have that because they decided to charge you for S172 for not sending the NIP back.
To have enough evidence for the S172 they have to not have received the NIP, but they must have had the information otherwise they couldn't have charged for the speeding.
As I pointed out above the CPS cannot answer this particular argument in your situation without appearing incompetent or malicious, so they may well fold. Please read my whole thread as it's explained in much more detail there.