@I-LOV-MONEY when you file an appeal the tribunal sends a notification both to the motorist and to TFL informing the parties that the PCN has been appealed and a hearing has been scheduled. If TFL get that email while the discount is still on offer, TFL freezes the discount so even if you lose the appeal, the penalty stays at the 50% rate. Of course there is no guarantee that TFL will continue to do this, but they have done it consistently for many years so you'd have to be exceptionally unlucky for them to happen to change their policy next week.
Anyway I'm going to drop you a PM in case you'd like me to represent you.