Hi all, Just to clarify:
I am less concerned about the Barking to Paddington route where I can pay PAYG oyster (where the difference between peak and off-peak is not great), but more concerned with the GWR leg of the journey. Obviously if a through journey from Barking to Kemble was cheaper, I would opt for that.
Weekday travel, no set arrival time in Kemble other than it being before midday, off-peak therefore is ideal to minimise cost (I appreciate from previous replies that off peak means different things to different train providers) but my priority is to get there at lowest possible cost as I would have to do this journey once a week, and sometimes twice a week, so over time, the savings would add up.
Dont have any railcard, but may consider getting a Network card if it lowers the cost up to Didcot, providing I can still get there before midday. Return journeys - dont really mind when as long as I can get back to London some time in evening.
ideally want to find a set up that saves cost each time, eg if advances were made available, I can plan and purchase weeks in advance to save costs.