Should i get a moped when i am 17?

Insurance costs for a car would be very expensive. One way you could keep this to a minimum would be to consider buying an older 125 such as the Honda 125 or Vespa 125 if you would prefer a scooter, and insuring it as a classic with a company such as Carol Nash. The early 125 Honda's were almost unkillable and if you can pick up an early 125 Benly you would have a bike that would appreciate in value as a collectors item. I bought a 35 year old 650cc Yamaha at a very reasonable price last year and it still runs like a dream as well as having novelty value. A moped would give you transport but would not provide any cachet or be half as much fun. See if there are any RAC/ACU organisations in your area as this will allow you to learn to ride safely prior to you buying a bike.