Make your reservations for the Eurostar as soon as you know your travel plans. 

There is a limited number of pass holder seats on the Eurostar between London and mainland Europe. On popular departures and during high season those sell out weeks, and sometimes months in advance.

The best place to see the availability of passholder seats and make reservations on the Eurostar is 

https://www.b-europe.com/EN/Booking/Pass#TravelWish

If you don't get any result, press "later trains" and eventually you will find the next available connection. 

If you have a mobile pass you need to generate a Pass Cover Number in order to make the reservation at b-europe. You do that here in the PCN generator:

https://community.eurail.com/news-and-announcements-39/pass-cover-number-generator-is-live-5653

Hey,

if you tell about what things you are interested in, then it will be easier to advise you…
Museums? Parties? Nature? Sports? …

In general you are choosing expensive destinations. Especially in Amsterdam the hostel prices are ridiculously high since Corona ended.

hiii, so i was thinking the normal tourist popular things, like the eiffel tower and stuff like that, this in general.

thank u so much, this really helped me!!!