Interrail passes

https://www.interrail.eu/en/autumn-sale/global-pass

Can anybody tell me more about them and can you say take a return to Amsterdam and a return to Germany or is it better to just book via Thalys?

Not sure what exactly your question is, but here's a fairly comprehensive guide on Interrail passes: https://www.seat61.com/InterRail-pass-guide.htm
You can go to Amsterdam and Germany, but you are only allowed two journeys in your home country.

U-Bahnfreund said:

Not sure what exactly your question is, but here's a fairly comprehensive guide on Interrail passes: https://www.seat61.com/InterRail-pass-guide.htm
You can go to Amsterdam and Germany, but you are only allowed two journeys in your home country.

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And, most important, you have to pay a Passholder fare of 30-35EUR on Eurostar. However, it is potentially very good value if you live a long way from London and don't mind a full day's travel.

As others have stated, there's lots of info about when an interrail pass does and doesn't make sense, but I'd add that the best offer recently was 1st class for the price of 2nd, and that an interrail is generally best value for lots of long journeys in a day, which doesn't fit with your usual desire for sub - 4/5/6/7 hour journeys.