Off to London in a few weeks for 48 hours - Friday to Sunday. Coming from the west, along the M4. Can anyone recommend somewhere where we can park the car for two nights and then get a tube the rest of the way in? Years ago we parked at Westfield but I think the congestion zone has been extended and we'd now get charged for driving that far into London. Trying to keep costs down as much as possible and think this will be the cheapest option.