The Yoga Show 2010 will be held from the 29th-31st of October at London Olympia (near Kensington). The event is becoming pretty large, so it’s best to sign up for the free workshops in advance so as to avoid the queues and possible disappointment of not being able to participate in the workshops that interest you.
I think it is a good idea to prioritise your free workshops. Chances are that you will not be able to attend all the ones advertised due to the number of applicants.
In my opinion, The Yoga Show has become a large sales event. If you need any new yoga equipment, clothing, books, etc... take plenty of money with you. If, on the other hand, you are looking for something a little more spiritual, you may end up a little disappointed.