You should consider one of the many fisheries in west Essex (accessible by M25 or A13). You can get over the water (Thames) by either going through Blackwall Tunnell or Limehouse Link and then onto the various main roads fairly quickly (if you go at a decent time). Birds Green in Ongar immediately springs to mind, as does the Warrens' Square Lake (near Stanford Le-Hope, Essex.) Churchgate Lakes in Battlesbridge (perhaps not so west Essex anymore) is worth a punt, I had 11 Carp out out of there the other week. There's loads around Brentwood. If you want to travel a bit further round the M25 there's an abundance of Pits, Commercials and River sections around Waltham Abbey, Cheshunt, Broxbourne and so on, mostly managed by Lee Valley, so have a look at their website on Google. Feel free to ask any specific questions on particular vanues, I'll try and help.
There's loads of places down in Kent, Sussex, Surrey....
In your area you have Rotherhithe Angling Club, as far as I know they own that ditch of a water next to the shopping centre at Surrey Quays. Allegedly (very allegedly) there's a couple of huge carp, possibly high thirties, that have never been caught. Who knows? You can also check out the various docks around Canary Wharf etc, they are fishable, but I'm not certain how you can get a permit, nor how hard (and I use the word "hard" knowing it will be) it is to catch fish. Might be better off gongs to Billingsgate next door, if you're in the area.