rich,
Indeed the autothrust will go active (once you come back to the CLB detent on all engines or the MCT detent on an engine failure) but bringing the thrust levers below either of these two positions will just limit the thrust manually.
One thing to remember however is that if the speed (managed or selected) is below your current speed then the thrust will go to idle.
Assuming this is not the case all that will happen is the thrust will follow the 'doughnuts' and other effects are dependant on the mod state of the a/c.
On ours we now get a chime every 5 secs or so and an ECAM warning that the thrust is 'limited'. Our FCOM specifically warns not to use full flap at high weights when flying level due to the large thrust requirements.
The implication is that of course selecting TOGA (as in your example) will also activate the FDs into the GA phase. Thus if you were set up for an ILS intercept, selecting TOGA will have the FDs cancelling the ILS and intercept. It would then require some nifty button pushing to get things back on track. Or of course one could turn off the flight directors and fly raw data.
idg