For brick work I use embossed plastic sheets from Plastikard or South East Finecast, go for 7mm brickwork as it works fine with 28mm (I'm assuming that's the scale you're building to). Pappa Midnight uses a different technique altogether, he scores the brickwork into blue foam, I havent tried it yet but I'll give it a bash when I have more time. Look up work by Overlord too, he uses the same method.
For building inspiration I get it all from this forum; Overlord, Svennn, Pappa Midnight, AndyM, Malamute, Jimbibbly, gamerMac...... I could go on.
For the buildings themselves I trawl books, the net or go for an explore around London. If you cant do it in person there's always Google Streetview.
Hope that helps.