The only point to watch for on the low priced tickets from full service carriers - typically these are totaly restricted. No changes under any circumstances. Use as issued or throw it away.
Both EZY and FR offer a fee to change per sector - plus any variation increase in the price of the new sector over the one paid for. This will be same routing just alternative time or date. This provides a flexibility that you cannot get from the full service carriers - at these prices. So be sure that you are going to use the ticket as issued.
Earlier this year my mother had to throw away a £90 (or so) BA ticket for an internal flight and found that her insurance company did not agree with the doctor and refused to pay. Unfortunately, no choice of carrier on that route.