Well a couple of months ago I went from Denby Dale to Huddersfield p4.... But you're right that p8 isn't accessible from that line.
Re Huddersfield, could an Adelante fit its first 3 coaches into platform 6, and the rest of it foul the p5 line but not p4 or p8 lines? I think it probably could, though would doubtless cause issues with overlaps and signal sighting.
I had thought I'd seen a crossover to get to/from p4 and the Penistone Line
As for p6, I doubt it, for two reasons.
1. The train would be miles in front of the signal (and possibly in a situation of activating the next track circuit)
2. The two bays have derailers on them, so I suspect fouling the end of the line would foul up about 3/4 of Huddersfield station!