I ran an octavia 1.8 diesel L&K for 6years 80k miles from new and was a fantastic car and averaged 55mpg mixed driving with 60 mpg on a steady motor way run
Compared to the wrxd 46-47 which i replaced the octavia for and my classic turbo which still gives me 25mpg it was cheap motoring
The fabia VRS old style was on of the best cars I ever drove as a courtesy car once
Power was fantastic and I would imagince similar mpg too
It's a small car but ok for a couple ,looks good to
Check out bri skoda website for opinions
But for 400 miles a week I would go the octavia diesel route as it is a bigger car and more motorway comfort
Taxi drivers run them as they can cover 250k+ mileages and are built to last
And parts are Very cheap. Too
Very good image skoda have now
Look at the jd power surveys they are always top