Thanks for all the info. Yes you are correct. I checked sbb.ch for a trip between Zurich and London and the display along with the price is probably the fastest of any rail booking site I’ve ever seen.
What is also good is that the booking conditions are also displayed.
I also checked raileurope.co.uk and it too will display Zurich-London with prices and so on. But this site is not so fast and clear as is sbb.ch
The RailPlus card is a good tip. But note that certain high-speed trains (including Thalys and Eurostar) will not grant the discount to RailPlus cardholders.