Easyjet...Advice please for changing flights after flight gone...

Sam_Bam

Just looking for confirmation of what Easyjet Flight Club customer service in France have told me.
Have a return flight booked from Bordeaux to Gatwick July 17th - July 22nd. Myself and my two children.
Easyjet have cancelled the return flight (twice!) on July 22nd. The July 17th flight is still happening.
I want to change my entire booking to another flight later on in the summer, therefore not paying any extra if the new flight is more expensive. 
I'm not sure of the new dates yet so I cannot change to a new flight until the outgoing flight (which hasn't been cancelled) has gone. 
Easyjet Flight Club customer service in France have told me that I can still change my flight even after the outbound flight has gone - I won't lose my chance to change the entire flight.  
Can anyone tell me if this is OK to do?  I'm a bit worried that if I do nothing until after the outbound flight has gone, I lose my right to make any changes to the booking.
Thanks