1. I hold to the 'peccability' of Christ, among there are many orthodox Christians.

[off-topic for this thread, however].
2. The issue of "impeccability/Peccability' is not relevant.
3. The Athanasian Creed, however, is salient and very relevant since it is a statement of what the Church confessed and continues to confess in regard to the two natures of Christ and their relationship. Thus, for me, the answer is quite simple. There are several examples in the NT where the God-man, Christ Jesus demonstrated and experienced all the temptations, woes, consternation, etc. of the common man. Even from His youth He grew in knowledge, strength, etc. as every human does. The point being that it is BOTH TRUE that the divine and human natures of Christ are inseparable, likewise they cannot be 'confused/intermixed'. The ultimate example is His crucifixion where Jesus Christ suffered, was crucified and He DIED!! God did not and cannot die being the owner of the attribute of 'aseity' (self-existent) and thus eternal. Thus, the human nature did not know, but without question His divine nature was privy to the time and manner of His return was infallibly known, having preordained ALL THINGS; including the means and the end.