It is rarely possible to upgrade and when it is, it's expensive. To book a 1st class seat reservation, you need a 1st class pass. Simply buy a 1st class pass : the price difference is small.
London - Edinburgh : free seat reservation available on LNER (seating map)
Paris - Brussels : 27€ for the direct Thalys (32€ 1st class). Cheaper to take a TGV to Lille (limited 10€, then 20€ in both classes) and then 2 IC trains to Brussels
Brussels - Amsterdam : use the IC -> reservation not possible so show early and you'll be good. Otherwise it's the very expensive Thalys.
With a 1st class pass you get free seat reservations in Germany, Austria, Czechia,... through tickets.oebb.at (3€ per train in 2nd class). 4,50€ per journey on bahn.com (not needed for your itinerary). Sometimes there is a seating map.
AFAIK it's not possible to book a seat between Prague and Munich. Show early and you'll get seats. 1st class is less crowded anyway.
There is a Munich - Venice night train if you'd like. Very popular so book well in advance. Again through tickets.oebb.at
Also use the same website for Italy : 13€ for Frecciarossa high-speed trains and no booking fee.
Let me know for questions
London-Edinburgh, rarely is 1st class so worth the money as it’s there, you get compilmentary service (drinks, small meals, snacks). LNER lets you book and choose seats, enter 0 for “reference” when doing so. Elsewhere on your journey, it’s probably worth the money if your budget isn’t really tight. The price difference is small, in the end, I think, compared to what it is when buying separate tickets.
Edinburg- Glasgow is such a short journey that it’s probably cheaper to get tickets instead of a travel day (unless you have one to spare).
For TGVs inside France it is possible for a little difference to use 1st class with a 2nd class pass. You have to book it via https://travel.b-europe.com/Eurail-GE/en/booking-tgv#TravelWish and you need a cover number
If you travel during high season, do make seat reservations between Berlin and Prague, and Prague and Munich. I travelled there last summer at the end of July, and the trains were extremely crowded. Luckily, my daughter and I had seat reservations. If the trains get too crowded, everyone without a seat reservation will have to leave the train.
@AnnaB How did you manage to reserve Prague - Munich ? ALEX (the operator) says that it is not possible but you can still make one for the Czech part (through cd.cz)
At least last year I could make reservations through DB.
@AnnaB How did you manage to reserve Prague - Munich ? ALEX (the operator) says that it is not possible but you can still make one for the Czech part (through cd.cz)
In that case you just make reservations for the Czech part.
@AnnaB How did you manage to reserve Prague - Munich ? ALEX (the operator) says that it is not possible but you can still make one for the Czech part (through cd.cz)
It should be possible to book reservations via DB, ÖBB or CD but only 30 days in advance.
- and how do you validate your tickets? I see people getting stung with this mainly in Italy.
You don't. It's enough to have a pass and (if required) a reservation. Nothing needs to be validated.
