1. Backhaus175 Ashburnham Road, Richmond
2. London Fields Brewery374 Helmsley Place, London
3. Bavarian Beerhouse190 City Rd, London
4. Octoberfest Pub678-680 Fulham Road, London
5. Escapade Fancy Dress & Party Store45-46 Chalk Farm Road, London
6. The Wurst Club56-57 Cornhill, London
7. Stein's55 Petersham Road, Richmond
Here you'll find all manner of teutonic baked goods, from go-to pretzels and strudels, to the more obscure cameroon doughnuts (made from "quark-dough" and covered in cinnamon).
Conceived by a pair of barley-pop enthusiasts over a pint of the very thing they're so enthusiastic about, Fields is housed in an open East London space with its own outdoor seating area, where they'll be crafting six different beers, a number whittled down to after an initial "experimental mass fermenting effort" -- oddly not a euphemism for uni.
Labeling themselves as "the UK's only German restaurant chain", the BB offers traditional pork shanks & knuckles, oompah bands, and waitresses in dirndls alongside a huge selection of Teutonic draught beers.
A pub that "celebrates Oktoberfest all year around", the OP's menu has traditional pork knuckles & shnitzels & 85 German beers, while also holding poker tournaments & pool competitions during the non-october months.
North London's finest fancy dress outfitters, Escapade will outfit you with everything from steampunk to The Stig.
It's well-known that Germans produce the best wurst & easiest to swallow pils, so consume them together along with more meaty & wheaty Teutonic delights in a nice-smelling WC: The Wurst Club, a snug fast-casual foodery in The City.