For Members and Guests car parking is free provided you register the Vehicle. THis can be in 2 ways:-
By White list from details on Membership Form or advised to Secretary via Door hosts. Once registered then you do not have to do anything on subsequent visits.
Register in foyer of Conference Centre there is a tablet for car registration full details are shown on a card. Rember that you have to do this on every visit until you are listed on the white list.