Yes, as just mentioned with IO you *could* be charging as low as 7.5p at home.
But agreed with previous comments on this thread, in London, Ubitricity is a godsend. Really convenient when they are installed in resident bays that are not so crowded, it was my case previously and never had an issue to charge, and you can leave your car overnight or more..
Most of them are still at 32p/kWh, it's not cheap vs. what it was before but given the current market rates it's still ok.
I would avoid Source London as they are much more expensive and charge by the minute... so only if you really need to
And there's also the free points in most larger Tesco's and Sainsbury's... (but for how long?...)
So overall charging in London is very much manageable, definitely more expensive than home charging, but currently, still lower than owning an ICE. With the business tariffs freeze announced today, we can hope that it will stay this way, at least in the short term...