Completely what it says in the title. And in the abstract. But with a "please" and a "thank you." I, obv., don't want to miss it, but I have limited London time, and wish to avoid superfluous queing.
Generally, if you turn up good and early you'll be given a number which guarantees that you'll get in provided you're there on time. Once you've got that you can wander off and do something else.
