Cameron Hall can be accessed any time the front door is open. However, the door is not opened every day 9am to 5pm like other buildings. It is opened ''on demand'' (usually by Club Presidents or other entrusted people). During semester Cameron Hall will be open a lot, and sometimes during the evenings also. It might be wise to phone ahead to check whether anyone's in.
If you want to get to Cameron Hall from off the University's Crawley campus have a look at the club's Contact page on its website41.