My understanding is that the roads will shut to all traffic (inc peds and cyclists) between 1 hour and 30 mins prior to the caravan arriving and this makes sense in town centres where there will be barriers. Once the caravan has gone past, the road crossing points will open again until (I guess) 30 mins before the peleton is due to arrive. But on the moors / passes I expect the lower parts of the climbs won’t be barriered since we’ll all be stood between the stone walls and the road itself, I would think you’ll be able to move across/around the road within reason.
So if the OP can join to Oxenhope-Hebden road from the tops, then I would think he should be ok. If you try and join the road from Oxenhope or from the Hebden side, I would think it will be barriered off to all traffic from 30 mins before the caravan arrives and won’t reopen to pedestrians / cyclists until after the last car (so 3 or 4 hours).