Many Agreeables have suggested going to Westminster to watch this and taking a bike, walking in cleats etc is a bit of a hassle, so the suggestion is to get a travelcard and go by train.
A group will be meeting at [b[color=red]]East Croydon Station at 10.00am. [/color][/b]This may seem a bit early, but there are events from 11.00am and the Citcle Line is closed that day for engineering works so may take a little longer to get there.