I am going to take a day trip from London to Stratford-upon-Avon. I am looking at round trip from London Euston Station to Stratford in July 2024. It is an express train to Birmingham then regular train to Stratford. On the Eurail app it says seat reservations needed. When I click on it says 1st class or 2nd class. I clicked 1st class and nothing happens. Is it too early for seat reservations? Do I need to look at another site?? Any suggestions would be helpful. Thank you.