Just curious - are you on your Red or Green p's?
From what you have said, it looks like you have a good chance winning in court due to the lack of "proof" and the fact that all these things are taken into account
1) "Bumped radar" so no speed (I know that this does genuinely happen though.. and is quite common).
2) Footage - group of cars.. no direct speed/proof you were doing x speed.
AFAIK a HWP officer is trained to "determine speed". And this is permissable in court. So if you drive past a HWP cop who has no radar/lidar evidence etc they have been 'trained' in determining speed.
I guess this factor, and at the end of the day its your word vs the cops are the only downfall... IF you do fight this, definitely use a Solicitor.
I regret never fighting my 1st speeding offence.. still makes me angry to this day lol.