The last is theory and will not work in practice. Its super busy this summer and you did not clearly state for what period. These under the chunnel €* trains are immensely populair now. But both these and the superfast Thalys Ams-Par also suffer from many sets out of service-both staff shortages (in about all forms of transit) and lack of spare parts (there is a war going on-in a country that did deliver a lot of these).

There is another page by seewulf which tells you howtodoit via other and cheaper ways.

AND the age old trick of dedicated passusers still holds: you are only looking at the superfast hi-speed trains. BY using other local trains=takes longer, more changes, NO REServ needed, one can do it all the time. This will not work for GB-continent, but Par-Ams: use FRench TGV till LIlle (must be REServed, but is hardly ever a prob)-change-train to Antwerpen-admire its railway cathedral-then hourly train on to AMS.

IN GB -on normal service (never garanteed there) there are trains ev 30 mins Lon-Edi-no need to REServe, but can do for free at a counter in GB.

If you give your planned travel details (departure date, time and route) here you will get help to see if it is possible to make reservations. 

July 29 London to Paris anytime

Aug 1st Paris to Amsterdam

I have the same problem. We are a family group of 4 and holders of interrail pass.

We will be in London and we want to go to Brussels on 26/07. 

What are my choices ?

You can look here for Pass holder seats that are left and also book here with a paper pass cover number, with mobile pass request it here. 

Booking Site: Pass fare Thalys and Eurostar | SNCB International (b-europe.com)

please keep in mind that almost all Eurostar trains in the next weeks are full. Only full fare tickets are left via eurostar.com

The earliest Eurostar with 2 free pass holder seats is in the evening of the 31st of July.

There is a limited number of pass holder seats on the Eurostar and 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 on the Eurostar is 

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

From London to Brussels the first available departure with 4 free pass holder seats is in the evening of the 31st of July.

Thank you AnnaB. I saw that too. So, what other options do I have to get to Paris on July 29th?

Here is the answer to that question given to a person needing to get from London to mainland Europe.

https://community.eurail.com/train-connections-reservations-47/train-from-london-to-paris-fully-booked-on-16-18-july-5822?postid=26250#post26250

If you want more details on any of the options, please ask in a new topic.

on kayak , through eurostar i can get a train ticket from london to paris on my travel date. does this seem right? it’s a little more, but not a lot of extra $. would i still need my eurail pass?

There are 1st class passholder seats on the 26 July on the 08.16 departure, same for the 27th. Obviously only valid with 1st class interrail.

Ooo very sad. Can I change my 2nd class to 1st? 

@Adena Astrowsky  Completely understand what you’re going through, just had a really similar problem with my passes/ reservations.
I know that doesn’t help at all though but thought I’d chime in that this seems to be a common theme with Eurail

Seat Reservations non existent only after I bought Passes!

i am looking at booking train tickets through Eurostar so i can get to paris on 7/29. i don’t see any other options at this point other than flying and i would rather take the train. if i don’t use my eurail pass can i get a refund?

There are 1st class passholder seats available on the 20.01 London - Paris on the 29 July.

For non pass fares Eurostar is quoting per person  £155 evening and £195 in standard class on 29th. Have you found cheaper?

it’s about $200/pp. but is there a way to upgrade my eurail pass to first class and then book through eurail instead?

Exchanging passes is possible as long as they were not sold in a promotion with extra restrictions and are unused.

Read here:

https://www.interrail.eu/en/interrail-passes/ordering-info/refund-exchange-policy

If you are going to exchange, you need to make sure you are eligible.

Also I would say that you would be advised to buy the Eurostar reservations first as those fares are likely to be gone soon, but only if you are sure you qualify for an exchange.

is it worth it to upgrade my eurail pass to first class? how do i do that? and can anyone see if i can travel from paris to amsterdam on aug 1?

thank you for the info on refunds/exchanges. i was reading that earlier. do i need a eurail pass if going through eurostar? 

You can't book pass reservations on the Eurostar website (sadly, they removed that possibility). You can call them but they will charge a €14 booking fee. The B-europe website will only charge a 4€ booking fee per order.

Echange policy:

https://www.eurail.com/en/eurail-passes/ordering-info/refund-exchange-policy

Check availability (aso Paris - Amsterdam):

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