I"ve just spoken with the venue and this is the situation with parking.
You will get charged for parking upto 6pm. The casino can validate your ticket from 6pm onwards (so that bit should be free).
Take a ticket when you arrive at the carpark, get it validated in the casino, and on your return just pay the charge for up to 6pm at the machine.
There is direct access to the casino from the carpark. When entering the carpark, hang a left and follow it round, you should see a Grosvenor sign with two sliding doors and lifts to the casino.
The carpark is open 24hrs.
