We will be going to London (family of 4) late July- stay 3 nights and then go to Oxford, Warwick castle then stay outside of Birmingham (so the Oxford/Warwick is one day). We don't need a car in London but are trying to figure out where to rent a car. if we take a train to Oxford, we have to figure out luggage storage in oxford then get the car (we really need the car after then). If we rent from London, we have to figure out to avoid the congestion tax area and then what to do with the car in oxford. We'd appreciate some help!