map of the postcodes with some areas contained within
And the boroughs

Postcodes are directional so as long as you know what postcode something is in, you know which direction it's in from you. And since every streetsign has the postcode after the streets name, you always know where you are.

Best shop is Condor, it's a bit upperclass though. It services mostly two types, people that can afford the latest carbon fiber doodad, and messengers/track riders. Very close to Condor is Bikefix. More your average LBS with knowledge of fixed. Mosquito Bikes in Angel is good, as is BrixtonCycles but it's all the way down in Brixton. Evans is the devil-incarnated McBikeshop - stay away from it unless all you need is consumables.
Cheap eats and booze... well... not really. An avg pint is £2.20 to £2.80 (that's about $5 !)but your avg can (tallboy) from an off license (liqour store) is just a quid. The Duke of York pub on Clerckenwell EC1 is the messenger spot.