I think you are talking BMW MINI Cooper, not the old one.
I also suggest you don't buy this as it is very easy for a new driver to get the car scrated. It is very often.
Some new drivers will think of small car like k-car. However, please put in mind that when you start by a small car, you will be painful in getting up big car later and the most important one, like k-car. The crash test of k-car is usually bad, that could be very dangerous for new drivers. I don't see new driver don't have their car scatched or even crashed for the first year. Be very carefully.
Usually people start driving at toyota corolla, Honda civic, Nissan sunny. They all are very good as a start. That's because they are most popular and not need knowledgeable understanding on car maintenance. Among them, I will suggest Nissan Sunny because it is the most cheapest in price. That doesn't mean Sunny is bad among two others, that's just because of the brand, traditional image, etc. As Nissn Sunny is the most cheapest, you can buy a newer car which could imply lesser problem, headache on maintenace.
From my experience, new drivers get driving everyday in six months can get a reliable driving skill relatively. In fact, I also change to another car after six months drive since I got liscence.
For website, you can check
www.28car.com and
www.car8.com
Many private sale.