On Weds we went to the WB Studio Tour in Leavesden to see the Harry Potter sets with my friend Sarah. It was absolutely incredible, but I don't recommend taking the tour bus that they suggest. The only allow you 3 hours in the facility, and if you get the audio tour, there's absolutely no way you could finish in that amount of time. I'd say you need about 5 hours there if you actually want to soak in everything and if you want to be able to have a solid look around the shop.
Either way, the scale of the props and sets and the sheer amount of information that they have preserved was breathtaking. I will for sure be coming back again to get even more!