I did it about a year or so again. A slightly surreal experience. Not really set up for the general public. Not exactly sure what I was expecting, but there is no real associated "experience". Flew down to LHR then had to make my own way to the training centre (taxi driver had no idea where it was. I think you can get a crew bus but didnt fancy that.
Arrived at centre and again not really sure where to go (it was a saturday) so not many people about. Eventually found a security PortaKabin. After numerous phonecalls, I was told to wait in the street. Eventually a charming retired Captain appeared and took me and my friend through to a small classroom. Rather than being treated like a special occassion, it was more like "why on earth have you chosen to do this".
Anyway we were scheduled on the 757. It was being used by El Al pilots which ran over time into our time slot, we were then ushered on and shown around. The simulator then failed twice and had to be rebooted (which took 30 mins).
Decided to split the remaining time between me and my friend which was probably too short. We got a little extra time because of all the delays at the end, but we had to curtail this as we had a flight to catch. Because of the rush, the Captain drove us back to T5 which was a nice touch.
Great to get a shot on a real life simulator, but it was far from the "experience" that i was expecting, especially for the money paid. There were lots of simulators lying empty so I wasnt sure why there wasnt availability on other aircraft, presumably its trainer dependent too. Did enjoy it but it could be made so much better.