Last year there was plenty of redneck music. I can only comment on Manchester, but I personally thought the venue was a bit small., and a bit of a let down, it took me about an hour to look at everything, then I was getting bored. There is a large stage with live music with different bands throughout the day. There is usually a weber tent and they give 15 -20 minute lectures throughout the day on smoking and BBQ'ing, great if you are a newbie but not so if you are more experienced. There was maybe 10 - 15 stands selling food such as pulled pork, sausages, burgers and planked salmon etc. There was also a couple of beer stands, a promotional item stand that was selling Grillstock merchandise.
While all that is going on the BBQ teams are cooking away behind their stands so it's good for a natter and occasionally there are freebie bits of food on offer, and towards the end of the afternoon the BBQ Competition is judged and that's about it . I think there was also a chilli eating competition and some other competition going on.
I don't know if the Bristol or London events are larger, It was on Albert Square which is about 200 meters x 200 meters or maybe a bit smaller.