Hire a car in London from one of the international companies:
In order to rent a car in London cheaply, you must be 21 years old (only people over 25 years old can count on luxury cars), have at least a year of driving experience and provide a driver's license, as well as a credit card. It is not possible to rent a car without a deposit in London.
Prices vary from 17 GBP (for example, for a Peugeot 107 Mini) to 342 GBP per day (for example, for a Mercedes S320 CDI luxury class). By the way, the further away from the center the company is located, the cheaper the car rental in London.
