great does this work with railcards as well?

No I have a railcard & when was last advertised @ £20 it did not deduct any discount as was still way cheaper than the standard price.... hope that helps x

Didn't work for a south west journey I tried

I just checked a trip from Fareham to Brighton next Saturday and it came out as £15.40 for a day return, I do remember from before they said if you have to change services to another supplier the discount wouldn't apply so just make sure you are using SWT

Not available 15th-19th Feb (school half term?) and the Easter weekend........due to "capacity factors".

Don't overlook that SOME SWT routes are included on the Megatrain site with cheap Advance type fares available, (sometimes from as little as £1 for totally antisocial hours trains).
https://uk.megabus.com/megatrain.aspx

Nowadays they seem to try to keep their overall route diagram a secret, though MoneySavingExpert republished an OLD diagram [ie routes may not still be current!] to give you SOME idea
http://images4.moneysavingexpert.com/images/megatrain-map-v2.png

This is just a heads up but Can I just point out that regarding the mega train tickets they are point to point meaning you CAN NOT break your journey or start or end it at a more convenient station to you, in other words you cannot purchase it starting at Waterloo but because you live at clapham you'll jump on and off the train there instead. It doesn't work like that and people often get offended when they are given a penalty fare which is double the single fare for that journey so could easily be in the £100's depending on time of day. It is clearly stated in a pop up window that you must start and end your journey stated on the ticket and you click OK to agree to this.

Yes just seen that as I tried to book for 20th Feb, but have moved it forward a week :smiley:

Just bought mine & deal worked xx

Cheers