At the lower levels and especially at schooling shows, I see all types of saddles including close-contact saddles. USDF says "An English style saddle is required and a dressage saddle is preferred." So you can use a close-contact saddle.
However. If you are really serious about dressage I would highly recommend getting a dressage saddle. You aren't going to get points off for your turn-out but it will present a more polished picture. Also it puts you in the right spot so that you are most effective.
DRESSAGE, n.: the passionate pursuit of perfection by the obsessively imperfect -Author Unknown