I'm not sure if leasing is done over here... i've certainly never known anyone who has done it.
I'm not sure what you mean by 'what is the best way to purchase a car', but i've bought several cars since i have been here and have usually just found the cars by looking around car lots. Salesman comes out, you talk, you buy the car. What i found annoying initially is that they don't let you drive the car off the lot that day.... you always have to come back to pick it up several days later.
My current car, i actually found on AutoTrader.co.uk, cos i was looking for something specific. But it worked much the same way. I phoned the dealer, said i'd seen the car online and do they still have it.... made an appointment to come look at it, took it for a test drive, discussed price, agreed sale, and then came back a week later to pick it up.