Outward/ return journeys

I’m from the UK and have bought an interrail pass for this summer. My month long trip is being broken up by a wedding that I have to return for mid trip - no choice there. I wanted to travel out by Eurostar at the end of July but all reservations are sold out (unsurprisingly).
 

So, my question is, could I fly out to start my trip in Amsterdam, visit a number of countries, return home and then use the ‘outward journey’ mid August and travel by Eurostar then? (There is availability for the date I want to travel) I hope this makes sense!

Thanks.