For anyone expecting to arrive in the area early there is another event at the Flash earlier on the same day ( 9:30 to 11:30 ) shown on the WLCT website.
See
http://www.wlct.org/Leisure/Events/greenspaces.htm towards the bottom of the page.
It is perhaps more of interest to budding birdwatchers but could help complete a nice day out and get more of a day out for your fuel spend.