In Kingston

Wanting to go there for the IWACS free gig on Sunday as I'll be in London (central) already. But last time I went to Kingston for a gig, it was a nightmare that included a £20 taxi, 6 confused bus journeys, sitting outside a closed train station and an hours walk. And we missed the gig.

So whats the best way to get to/from there from central London, especially as it's a Sunday and what's a good sort of ETA, as a friend wants to know if I'll be back for the Superbowl