Citymapper (the app) will tell you the platform before they put it up on the boards in the station. Generally this is to allow the cleaning staff to have access to the train before the hordes descend.
[Other tools that display the online platform information that National Rail provides are available.]
You have to trust that they won't switch the platform on you at the last minute, but I've never had it happen to me.
And yes, the bike coach on those trains is usually at the far end of the platform from where you enter.
Citymapper (the app) will tell you the platform before they put it up on the boards in the station. Generally this is to allow the cleaning staff to have access to the train before the hordes descend.
[Other tools that display the online platform information that National Rail provides are available.]
You have to trust that they won't switch the platform on you at the last minute, but I've never had it happen to me.
And yes, the bike coach on those trains is usually at the far end of the platform from where you enter.