I would add an emergency tent repair kit: some Tenacious tape, silicone seam sealant, clingon clips and bungees, spare guy rope, spare pole length, and some duct tape or similar. I just keep these in the same stuff sack as my Delta Ground Anchors and big ripple pegs. I have been glad of it on more than one occasion, sometimes for patching other people's tents!
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.