No, this ONLY applies to this €* from LON to ´the continent-and the 45 mins advance is clearly posted on all tickets/RES-slips. In all other cases: as such 1 min is enough, the only thing you have to do is scan the big screen for which platform and run to there-in some stations this may take much more as 1 min. There are a few cases where the tickets state one has to be 2 mins before dep. on platform.

The assorted combined countries on this continent here all belong to the ´Schengen zone´ without any further regular ID/whatever checks. You may not even notice you are suddenly in another country. Registration of foreign alien devils is only done on 1st point of entry and only means scanning your passpt.

All in all not even different from going from MEL/Vic to SYD/NSW.

One small word of warning - most of the main stations are huge and can take 5-10 minutes to walk to a platform, examples being Rome, Paris and London Kings Cross.

Although there are only a few places such as Eurostar where an airline type security is present, I would take the “turn up with a minute to spare” advice with a pinch of salt. 5 to 10 minutes early is realistic to find your platform and then board and find your seat. In the UK they advise that doors will be closed 1 or 2 minutes before departure.

I live in Leeds and I assure you I need at least 10 minutes to get to the extreme platforms, not to mention the few minutes it takes to get through the automatic ticket barriers.

Stay relaxed and arrive in good time, If early find the bar. 

Many TGV stations have gates where you need to scan your reservation in order to access the train. Allow at least five minutes for this as you may be in the front half of a TGV train made up of two units. There is no access between them

It's a bit dependent on what type of train you take and in which station. For the long distance-train in big stations I would advice you to be a bit in advance at the station. About 20 minutes in advance will do. There can be ticket barrier gates (Nl, UK, sometimes France, Spain,...) and platforms can plentiful and long, sometimes with multiple levels, which means a long walk to find your train and a good seat.

No formal security or passport checks what so ever in the Schengen zone between countries. It are just trains, not planes! If (passport/ID) checks happen, it will be on the train itself, when you're on the way (like the border crossing between Denmark and Germany). 

Only exception is Eurostar of course, as mentioned above. Since that is traveling in/out of the EU and Schengen. I don't think you'll encounter any other check on your trip, besides that one. 

If it stresses you a bit, I'lld reccomend to familiarise yourself with floor plans uploaded in Google maps or open street map. If you zoom in on the station, you can familiarise yourself a bit with it with the inside of the station. Most big stations have that. 

In smaller stations for regional trains, where you don't have a lot of amenities, you can show up later and hop on a train. But still have a bit of a buffer, 5-10 minutes. There always can be an annoying set of stairs present that might cause issues with your luggage e.g., and doors often close 1-2 minutes before the departure time. Missing your train because of that, is just annoying. 

Enjoy your trip, travelling by train is usually carefree and comfortable!

Thank you for your help it’s exactly the information I needed