I know this was a no go, but if anyone is interested in the future or just for reference, this is the email I received from them
With reference to your e-mail sent to emma regarding exclusive track hire for road cars. We only tend to take bookings of either full days or ½ day and not by hour. Could you please give me some more details on what you would like to do and how many cars will be attending. The minimum number of cars on track is '3' and maximum is '12' but you will be looking at a starting price of around £2,000 + VAT (this price is valid up until beg of March and then we will revert to our full prices which start around £3,000 + VAT)
All cars must be road going and silenced to 100 dba.