Website URL: http://www.brittany-ferries.co.uk/faq/travel-information/what-is-the-earliest-time-i-can-check-in-for-my-crossing

What is the earliest time I can check in for my crossing?

The earliest check in time for both foot passengers and vehicles is between 2-3 hours before the scheduled departure time. Although this can vary according to the time of year.

Boarding will normally commence 30-60 minutes before the scheduled departure time. If early boarding is available this will be noted on your travel ticket.