I'm living in Hungary and I'm going to order a new Octavia with 1.4 16V 80hp engine. Tempomat is not an option for this engine, but available for all other engines.

This is a global Skoda policy? I say "policy" because several independent service claims they can upgrade any Octavia (in fact any VW group car) with tempomat.

Maybe the motor is too weak to accelerate under typical circumstances in the highest gear and/or to keep the speed constant.