I would probably go to Herne Hill, then Milkwood Road, Loughborough Road, Akerman Road, Mostyn Road, across Brixton Road to Lorn Road, Stockwell Park Road, a v short stretch of Clapham Road, then left onto Albert Sq and wiggle your way over to Fentiman Road then you're pretty much there - do you mean Vauxhall station or just the area? Hope that helps