No, for a U fare (which is the cheapest possible TK Eco fare) there will certainly be change fee + possible fare difference. It clearly states" Change with fee", i.e. you need to pay change fee.

You can look up the fare rules, incl. the change fee applicable, in ITA Matrix assuming that you are able to find the U fare.

The best advice is wait to book until your travel dates are certain. To book a U fare now with the knowledge that you may need to rebook the travel dates later, doesn't make sense/will be expensive.

Another strategy is that you book the U fare now and hope/wait for a schedule change of more than 15 min or a cancellation, which will allow you to rebook for free -7/+30 days, i.e. after such sch. change you have a fully flexible and refundable ticket until you either confirm the new rebooked flights or rebook the ticket (but keep in mind that you can rebook for free once after a sch. change so don't rush to rebook the ticket after such sch. change).