Elizabeth Redman, 29, was stopped after drink-driving in her white BMW on the major road on September 11.
Redman, of Eaton Avenue in Bletchley, near Milton Keynes, gave a reading of 97mcg of alcohol in 100ml of breath. The legal limit is 35mcg.
At Northampton Magistrates' Court Redman admitted drink-driving and was banned from the roads for 23 months.
Magistrates also handed her a community order with 80 hours of unpaid work.
Redman must also pay costs of £85 and a surcharge to fund victim services of £90.