When I get to the station this Sunday, I will activate the travel day. Is there anything else I need to do in order to travel? Do I need to add the journey to my pass, or do the physical seat reservations suffice?
You always need to add the journey to your pass.
Please see:
https://www.interrail.eu/en/interrail-passes/interrail-mobile-pass/getting-started
If I add the journey, it doesn’t give me a ticket as such as the journey added says “Seat Reservations required”. I then have the paper copy of the seat reservations. Is that all I need to do, or am I doing something wrong. Just want to check as despite adding the Eurostar journey there is still no option to “Show TIcket” in my Eurail mobile pass.
If I add the journey, it doesn’t give me a ticket as such
Yes it does. After adding the journey to your pass (and activating your pass and travel day), you can generate a QR code for the travel day and that is your ticket.
as the journey added says “Seat Reservations required”.
That's just for information. The app doesn't know whether you have a reservation or not.
I then have the paper copy of the seat reservations. Is that all I need to do, or am I doing something wrong. Just want to check as despite adding the Eurostar journey there is still no option to “Show TIcket” in my Eurail mobile pass.
That button will appear after you've activated your pass and then added the journey to your pass. Merely saving the journey in your trip doesn't do that. Did you follow the steps on the page I posted?
Also note that it's generally not a good idea to activate anything (pass, travel day or inbound/outbound journey) in advance. You can only cancel activation until 23:59 CET before validity starts and if something happens after that (e.g. you wake up ill), then it will be too late to cancel and you'll lose travel days. So it's advisable to cancel activation after you're done testing.
Figured it out! I didn’t understand that I had to tap on the sliding symbol - I was tapping elsewhere on the journey so it wasn’t properly adding to my pass.
Thank you very much for your help rydborgt.