Hi meglos
Thanks. I’ve done exactly that when starting my journey from a National Rail station. The problem here is that Woolwich is Elizabeth Line / TfL only, so it doesn’t have a manned ticket office. As Mike suggests, I could try at the nearby Woolwich Arsenal station, but the tcket office there isn’t always open. I’ve decided to buy an e-ticket using GWR’s app, as this is the most convenient option.
Regards
Ian