Will I be able to use the GWR▸ express services?
I went to London (and back) via Paddington two weeks ago, and was struck by the removal of almost all the semifast evening services that used to be allowed on an off-peak ticket. That's because the last time I went that way on a weekday was not only pre-Covid but before December 2019. All we were left with was Crossrail, plus the semifasts at 17:56/18:26/18:50/18:56 (all stop at Twyford).
The December 2019 edition of the T10 timetable had clear red markings to tell you which trains were not OK with an off-peak ticket. The current T10 has nothing of the kind, so the only way to know which trains are allowed is to use a journey planner and go through the list - rather tedious. I don't think there is still a leaflet listing them - or is there?
Given we were trying to avoid crowded trains, we gave up and spent the hour sitting in a 345, which had plenty of seats free. I did cope with the toiletlessness, but found the seats felt very hard after an hour. My sister felt the same, but was more irritated by the incessant stream of nagging announcements.
For the record, we used travelcards, but then we were going to zone 4 (for a family funeral).
PAYG▸ would be less but only by 30p, unless you go by the scenic route (via Ealing Broadway/Shepherds Bush/Willesden Jn/Highbury&Islington), so not really worth it. For anyone really keen to avoid crowded trains, I can recommend the GN service from Moorgate during the day!