Did you have to book well in advance? Much is it if you don't mind me asking.
I booked about a week in advance. It wasn't too busy. There were about 8 on my tour. I imagine it is much busier in the summer. The cost including the museum (which was well worth it), was £23 or £19 for concessions.
The show you a couple of bits you can 't access if you are just wandering around, ie The Press Centre, and Players entrance.
It kept me entertained for about 5 hours.