The Difference Between The "Cheapest" And "Flexible/Open Return" Options
Intercity UK rail tickets can be divided into 2 broad categories: "quota" and "walk on".
Quota Fares
Quota fares are the advance purchase, cheaper tickets and you will find these if you leave selected the "Cheapest" option on the home page under "ticket type" and they are available. There are a limited number of these and they need to be booked in advance, usually up to 1800 the day before travel. There are different levels of quota fares, as the trains fill up the quota fares become more expensive. On routes where they are sold, they are made available up to 12 weeks in advance so, if you're looking for the cheapest fares, you must book as far in advance as possible.
With quota fares you must travel on the trains you booked but with most of them you can amend your journeys but you must do that before you travel. You cannot just turn up and travel on a later/earlier train that you have booked as a quota fare. You must change it before you travel and you will have to pay the difference in price plus an amendment fee. So, the later you have to change your journey, the more it is likely to cost.
So, while they are discount fares, quite a few of them (particularly the cheaper ones) are non cancellable and they do not have the flexibility that you can just travel on different trains on the days you booked without changing them.
Walk On Fares
Walk on fares on the other hand do have this flexibility. These fares are featured under the "Flexible/Open Return" option under "ticket type".
While you may have booked to travel on certain trains, with Saver walk on fares (the cheapest walk on fares) you can travel at any time on the day you booked to travel outbound and can even travel outbound on a different day if you need to if you buy a Standard Open Return.
It is on the return journey that these fares' flexibility really counts. With these fares you can travel back any time up to one month from the date you booked to travel outbound.
So, if you're not exactly sure what time you might be returning or even if you might extend or shorten your stay, with these fares you can just turn up for your return journey as long as it's within one month of the date of outbound travel.
Raileasy does not have the option to leave the return date completely blank. We have found that most people know either exactly or roughly when they want to return, in which they can select either the "cheapest" or "Open/Flexible Return" option respectively. If you really have no idea when you are coming back, we recommend you buy a single under either the "Cheapest" or "Open/Flexible Return" option depending on how sure you are about your outbound time.
Walk on fares, as the name suggests, can be bought when you turn up at the station to travel but we recommend you still book them in advance because then we will reserve a seat fot you.
Walk on fares are also cancellable and refundable apart from admin charges.
Whichever option suits you, it is important that you check the terms and conditions of the fare you select. You can view these by clicking on the "details of the selected fare" link by the price of the journey you select and the "buy tickets" button. The terms and conditions of your ticket will also be in your email confirmation.