I had the luck to visit this as a child, before all the tourist side of it was shut down. I remember taking the bus past the giant turbine hall. A few facts I can remember:

1. Carol Vorderman did a lot of the engineering calculations, before she started on Countdown (probably only relevant to the UK lot).

2. They couldn't run powerlines from the facility to the grid as it's an AONB so they had to run them underground at a cost of £1M per mile for however many miles.

Great place along with Sellafield and the wind turbines in Norfolk for a kid to visit.