will people there help in case l have a problem on no one cares....??
10x for the help:)

You must validate & there is usually no excuse for not doing since the ticket punchers r everywhere inside the railway station, including near the train departure binary; in smaller towns is possible there is just one or two punchers & it is not impossible that one or two may be out of order when you're leaving; if so, the best thing to do is telling the ticket inspector as soon as possible. In those small stations usually the train themselves r ''short'' (a couple of coach or even just the engine), so it is easy to find them.

On trains like Eurostar, though, where now (unlike some years ago) booking is mandatory & the ticket is strictly related to one specific seat on one specific train validataing the ticket is not mandatory. That is because is simply impossible to use that ticket once again if the ticket inspector do not punch it.