The circuit may be hired for the purposes of testing, car set-up and practice.
Track Hire Testing times 10.00am - 4.00pm
General Testing Saturdays (from March until October) £20 per session Turn up and drive
Midweek Testing Midweek only £30 per session Strictly by appointment only *
Exclusive Circuit Hire Midweek only £100 per day Strictly by appointment only (maximum 2 cars) *
All sounds a bit cheap to me

They do all sorts of things like banger racing so i'm pretty sure they'd let us all on at once or do the time trial as planned, I guess they'd give us a group booking discount but even if we all went to a general testing saturday and paid our £20 it'd be fun!
cheers
Ali