If I were in London I would DEFINITELY be going to the  Safari Festival, the one day CAF run by Breakdown Press and devoted to
“the new wave of alternative and art comics from the UK and beyond. Taking place over one Saturday at the end of August, the festival is an opportunity for a curated group of cartoonists and publishers to exhibit and sell their artwork, prints and, primarily, comics, and for attendees to experience the best of UK comics’ avant-garde. The artists exhibiting have been selected for their innovative, fearless, diverse approaches to making comics; approaches to cartooning that Safari intends to champion.”
The festival is free; the location is Studio 2, the Shoreditch gallery space of London-based creative agency, Protein. You can check out the kind of books taht will be displayed at the Safari tumblr and the poster by Will Sweeney and Joe Kessler.
Exhibitors include:

Anti Ghost Studio (Babak GanjeiRob Flowers, Tim Stevens), Breakdown Press (Joe Kessler,Antoine CosséRichard ShortZoë Taylor), Calm & Collected StudioComic Book Slumber PartyComics Workbook(Will TempestLiam CobbTom Kemp), Decadence Comics (Lando, Stathis Tsemberlidis), Donya ToddEleni KalorkotiEsther McManusEyeball Comix,Famicon Express (Leon Sadler, Stefan Sadler, Jon Chandler), Faye Coral Johnson,Good PressGrace WilsonIsaac LenkiewiczJack TeagleJames JarvisJazz Dad BooksJoseph P KellyKus!Landfill EditionsLaura CallaghanMarijpolMatt SwanMike RedmondMothershipNous VousOne Beat ZinesOtto PressSina SparrowTreasure Fleet (Aisha FranzSharmila Banerjee) and Will Sweeney

Breakdown is one of the most exciting small press publishers I’ve seen, with books that explore both the experimental edges of comics and the traditional roots of storytelling by such Beat favorites as Conor Stechshulte, Lala Albert and Antoine Cosse. Breakdown Press itself is launching a new book by Jonathan Chandler, and you can see abit of that below, but the exhibitors all have the same spirit of cutting edge comics that won’t make your eyeballs bleed.
Report back on how things go, kids!