Another sufferer here, mine definitely eases with movement. First thing on a morning is the killer. Like Pilton Digger, standing still is definitely the worst for me.
First bout was in 2014 and I didn't attend in 2015. Not related. Second slipped disc happened during the first lockdown and I think it would have meant me missing Bearded Theory, not sure it would have stopped me going to Glastonbury. I would have just taken it easier, seen more of the Cabaret and Circus and not walked the 20-25km a day we did in 2019.
Once it's settled down, I have found the Renpho massage gun really good for relieving sciatic pain/
Hope you manage to make it