SWR's mixing desk website is willing to sell me a 1st day return for tomorrow (Tues 28) leaving on the 0645 direct service arriving 0831 and back on the 1900 service from Waterloo.
Its willing to sell me a weekend first super offpeak travel card and says its valid. National Rail website confirms the same.
Is this right. Can I rely on a print-out of the train website if a guard challenges me?
If you buy it in conjunction with that itinerary then it must be honoured, as a binding contract has been formed.
As has been suggested, it is possible you will experience difficulties using the ticket in line with the contractual validity you have been promised, but that does not remove the contractual validity.
You should give your name and address if any member of staff can be considered to have reasonable grounds to suspect a ticketing irregularity. IMO if you present an itinerary from SWR's website, in line with which you are travelling, then that is not grounds to suspect such an irregularity.
I would
not pay any excess demanded, unless you are unable to access the train otherwise. In that case, excess the ticket in line with what you are told is required, and keep the excess ticket and the receipt as evidence of SWR's breach of contract.
Equally I would not pay any Penalty Fare - a Penalty Fare is totally inappropriate in these circumstances.