This is the ferry company I use each time I go to Normandy because it is cheaper and faster than Brittany Ferries (Brittany Ferries from Portsmouth to Ouistreham: 6 hours - Transmanche from NewHave to Dieppe: 4 hours).

It costs me about £30 return without a cabin and £53 return with a commodore cabin. It's a big cabin with a 3/4 bed. It is supposed to be for one person only, but my girlfriend and I always shares it because the bed is big enough for two and it is always better than a cabin with two separate beds :-).

It is actually the best cabin they've got as it has its own showroom and toilet, a desk, and a WINDOW.

I advise you to travel at night (departures are around 11 in winter). You will arrive at 6 am French time and will have time to rest before you arrive.