bristol is 1 hour away .... id imagine cab journey would be an absolute max of 30mins .... barring any accidents Id say you should be fine . never any guarantees though id imagine you might be able to get a slightly earlier one though as there should be lots of coaches going that direction
Should be OK at that time of day. You're not swimming in time though and Bristol can be busy on the Monday so may not be a bad idea to spring for Priority.
Primavera has to evolve or die un/fortunately. I mean, I get it... I've been through similar ill-feelings with Leeds/Reading, Latitude, Tramlines festival etc, but the sooner one realises that maybe it's no longer a festival you want to attend, but there's others you want to instead, the more at peace you'll be. If there ever becomes a time when Massive Attack/LCD Soundsystem/NIN/Radiohead/The National can't get on any festival line-ups because of the new crop of acts, then you can legitimately be annoyed I suppose.
Plus it seems to be overlooked that, just because a certain act's touring schedule lines up, doesn't mean it's a done deal that they will or should play a festival. Maybe Primavera could afford NIN but they felt their fee wasn't reflective of their pull. Maybe they had unrealistic demands. Maybe there's some label/sponsor exclusivity thing going on. There could be a whole host of reasons.