I've had my Octavia 1.9TDI estate for 2 years now. I do a 12 mile run to work and back each day on small Devon roads :-( Always get 50 mpg or thereabouts.
On a long run in France, we are averaging 52 to 55 mpg and we don't use the motorways. It does go down a bit with the aircon on.
The other thing I have noticed since owning this car with the computer, I don't use the brakes nearly as much, but try to just take my foot off when necessary. Here in Devon you drive behind people who use their brakes every other second, every corner, every time they see another car. This, of course, will ruin your fuel economy. The car has just been serviced and brake pads are only 30% worn at the front and less at the back. The car is 3 years old.
Just love my Skoda :-)