Runstock is a great concept, its 5k laps over 8 hours with obstacles. It's open to familys and serious ultra runners, there is a challenge for runners to run 50k if they choose to.
The course is tough, it is very hilly however it's very manageble (dependant on experience) in 35/40min per lap. The atmosphere around the event was very relaxed, runners dropped in and out of the course as they wished for breaks, there are activities for kids in the event village.
Overall a well managed event but very costly. Race entry is £59 which is more expensive than a decent marathon, £20 for the ultra attempt upgrade and £30 for camping - that's all before travel and food. The site isn't the easiest to reach without a car, I got a taxi to the train station and it was £15 each way.
My full blog is at https://autisticrunnerjohn.wordpress.com/2018/06/10/ratrace-runstock/