Is there even issues with Percy Main? There's plenty garages in London which are much tighter than there which have managed to get electric charging within the sites.

I know it's off topic for this thread but Stagecoach Walkergate has to be the prime depot for electrics really, the 39/40 and 62/63 are the exact sort of routes which should have them imo. City routes from end to end running through some pollution hot spots aswell. 

The 56 would be the best route at Deptford if anything, running between 2 cities and again a hot spot (Tyne Bridge) and is mostly urban aswell bar a few fields around Nissan and Springwell. The B9's are pretty much up for replacement soon aswell.