Had gotten the impression that this was:
(1) a drop off/pick up charge; and
(2) it was way into the future, after the third rwy was in use (so more than likely never!).
If it is going to be implemented, (and other airports do it), it would need to be after the public transport improvements have been completed, especially from the south. Also, the first ten minutes needs to be free.
If the proposals are about traffic management within the central zone and I would imagine they are and face it, it would be very easy and cheap to implement - Cameras already exist and access is strictly controlled through tunnel.
I would be pretty sure there would be no "free" time.
Just a flat daily charge similar to the London central zone only worse - At least residents their get discounts and electric cars are free.
I believe this is inevitable and certain within a few years with or without T6/R3.
Just more reason for anyone in the UK to avoid this airport more and more.