The centre is great and I got this (well my dad) - is it not £275? If it's not - see you there!
I went recently there to drive all of them over a day for free. Boxster, cayman, 911, panamera and cayenne. Was a good day with everything for free, breakfast, posh lunch (which is nice but VERY small) and a lot of porsches.
The boxster and cayman were great on the simulated ice hill they have. They let you take them out on your own and basically try and spin it! The 911 was around their track and the other 2 out on the main roads.
Their test track is short but ok i guess for the purposes.
They also have forza to play on
Unfortunately, unless my dad buys another one i think that's the last freebie we get
Edit: they also have a fitness centre with a reaction machine. On my day whoever got the highest score won a ride in the GT2RS they had - you need to be tall to win this though

the guy who won was around 6'4!