When pricing your house don't let the EA over estimate the value of the good points and under estimate the downside of any negatives. You can be 100% certain that a buyer does notice value for money and that they get p*ed off if a house is clearly overpriced.
Being 12 miles from a supermarket is a negative especially if a "quiet rural location" can also be foung 9 miles closer in. An extra 18 miles 2 or 3 times a week soon mounts up in both time and money.