My first thought would be to check if the radiator fans are working. As a rough rule of thumb the check used to be even when cold if you start the engine and turn on the air conditioning the fans should come on. That's the way we used to check in say my 2001 Bora 4mo. Not sure if it still applies. Crook radiator fans is a bit of a VW bugbear so I assume it applies to Skodas as well. I guess the other way to check would be to pull up when the car is at normal operating temperature, leave the engine running, get out and see if the fans are running.