i practiced most my driving in central london, and i found it is good in a lot of ways
the dickhead pedestrains, piece of ****e drivers, the high amount of traffic and narrow roads etc really does help you become more aware as a driver and less considerate of other drivers (which is important because you dont want them pressuring you as you drive). i found that the traffic helps you get better control at the clutch too. all this makes it a relative breeze when you drive in other areas.
i live like 15 minutes away from russell square and most people around me are going to take their tests in barking (goodmayes) so it might be the same for you. initially i practiced driving around wide roads around stepney and went on to roads around poplar, roman road and the a13, now that im closer to my test im practicing more around barking. again i dunno if itll be the same for you.