Ferry from Santander to UK with young kids?
 

I have young kids and live in Spain. My parents live in the UK...and my partner hates flying.
Wondering if anyone has taken the ferry Santander to the UK with young kids?
Would it be a nightmare? (youngest is 5 months).
I'm worried about them getting seasick...if there's enough places to change nappies...if there are things to keep the kids entertained.

You need a cabin for such a long crossing. I don't know but I imagine it is available to you for most of the time on board, which wil be great with young kids. If you can choose try for one midships where any movement will be less.
There are indoor and outdoor children's play areas onboard according to Brittany Ferries.

Plenty of people take the ferry with young kids, I know my niece has taken it with her young boys a couple of times, starting from Portsmouth then, not Plymouth, one time on her own, once with her partner. She is working now so i can't ask her about the cabins, but Brittany ferries will be able to answer that question I am sure. Also about cots for the baby.

You might also ask the children's doctor if any prophylactic medication is recommended to prevent seasickness.