I've just been browsing the net at work and I've come across two events that Thorpe Park are going to be running in October / November.
Thorpe Blast - 7- 9th November: http://www.thorpepark.com/thorpe-blast.php - music playing throughout the park, could be hit and miss though depending on music taste!
Fright Night - 13th October - 2 November: http://www.thorpepark.com/fright-nights.php - halloween theme throughout the park with mazes that I've heard are pretty good!
Both look pretty good as there is something else to do beside going on the rides! And the park is open late depending on date till 10PM! Would anyone be interested in going?
As its just off the M25, I imagine a lot of people could get there quite easily? There is also a bus service that runs from Staines to Thorpe Park for anyone who wanted to come via train.
If a group booking / discount can be arranged it can be a fairly cheap day out