Booking flexibility

Helle ​@MelG 

You have some trains with mandatory reservations and some trains without mandatory reservations. And some trains which can be sold out if you don’t reserve in advance and soma trains with a lot of free seats. 

It is certainly advisable to reserve seats in the Eurostars from/to UK in advance because they have quotas for pass holders. 

Seat reservations are not always refundable, it depends of the countries. You will find more details here:

https://www.seat61.com/interrail-and-eurail-reservations.htm

It depends on your route and when you will be travelling. But eurostar is the most important one to reserve early.

The international trains between Germany and Netherlands/Belgium for example only have mandatory reservations in the summer.

Flexibility of reservation depends on the operator (But reservation bought from DB (Germany) for international and domestic trains can not be changed. Not sure for the other countries on your route)

Thanks for the link ​@Danhiel.  we have  Interrail Plus Pass, seat reservations are included in the pass excluding some like Eurostar. not sure how would that effect the reservations?!

Our planned route is London to Brussel to Cologne as the first leg , than Wienna and Bp. On return Bp to Salzburg to Brussel/Bruges and back to London.

Last time we used Eurostar we had 6 hours delay, if that happen again we would need to amend connection trains. 

Thanks for the advice ​@Marvin Heer . If I have an Interrail Plus pass can i just book another train if I missed one or change of plan, or the system would not let me to have 2 departure from the same location. on the same day?

Unfortunately the Plus pass is a bit of a pain when you want to amend reservations. Some (Eurostar, TGV) can be amended with the operator, which is usually easier than charging with Eurail.

Eurostar has free changes (time and date, not route) on its own website up to 7 days out, then it charges a change fee.

Others, eg DB, can’t be amended. You’re supposed to cancel them - which when I used the Plus pass required you to contact Eurail to do it manually. You’re not supposed to make extra/ duplicate/ Plan B reservations until you’ve cancelled the original, to prevent misuse.

However, in the case of disruption, this is fine. It’s explicitly allowed in the T&Cs to just make an new reservation if necessary.