Work done by the tension in the circular path will be equal to zero.
This is because body moves in circular path, the centripetal force act along the radius of the circle and motion is right angle to the tension on the string.
The Earth's perihelion distance is about 147,000,000 kilometers and its aphelion distance is about 152,000,000 kilometers. So, the change in distance is about 5,000,000 kilometers which translates to about 3,000,000 in Miles.
