Mate, I used to drive around near where you're at, a bit north, near Stepney Green and Bow, but it is a really chaotic place to take a test. If i was you, I'd book it for somewhere in mid Wales. On my test, the nearest motorway or dual carriageway is 90 minutes away, and we only had 2 roundabouts in the town, and the examiner was late too, so it was a 15 minute test.
Wish ya luck anyway mate, and hope that the examiner's a nice guy for you, and doesn't ask you for all those tough things, like traffic lights and reversing