There should be a few breweries closer than Meantime. Sambrooks is just south of the river in Battersea.
Looking north, Camden wouldn't be too far and they're open to the general public on Friday evenings; otherwise by appointment, I guess. I hear good things about The Bull, a posh gastrobrewpub up in Highgate, but I haven't been.
Your options improve as you go east: the closest to the centre I can think of is Saints & Sinners at BrewWharf in Borough. An opportunity to do The Rake and Market Porter while you're there. And Kernel's just a few stops beyond that, and then you have London Fields in Hackney, Tap East at Stratford and Meantime all in different bits of the East End.