I say Tribunal time.
I have logged on thee tribunal site to appeal.

For this one I assume I have to put in moving traffic (including junction box) contravention

and for this one I The contravention alleged by the authority on the penalty charge notice did not occur.
For the reasoning, I will apply what H C Anderson provided:
1. It is restricted to term-time only: then the council need to obtain the SoS's authorisation to a non-prescribed sign. But they haven't, because the only prescribed sign is every week, term time or not.
2. The restriction isn't term time only, which is what's conveyed by the advance sign. In which case IMO the signage fails the LATOR test because in combination those in the know might be tempted to drive into the area outside 'term time' but still be breaching the traffic order's prohibition.
Should I also add that there was no warning signs on the way to the road to be safe?