Kennels on cross channel ferries

We are relatively new dog parents and have always taken a summer break in France. Obviously we want to take Nash with us (he is 6 months now and a loving, lively cocker spaniel). We have booked a kennel on our ferry for this summer and wondered what experiences and advice my fellow caravanners have? We are in Brittany and around 3 hours from the port so not too bad travelling. Should we have considered the tunnel?

Cheers all and HNY!