Sleeping onboard is fine, I've done it many times now. The facilities in Braye are basic but clean, the showers are hot. As Martin says they are all swinging moorings, most of us moor stern on when sleeping onboard to avoid the bow where you sleep taking the slap all night.
However after doing this trip for a number of years even the hardcore are staying on land this year. The novelty seems to have worn off, and a warm comfortable bed that doesn't move isn't a bad shout for around £30 a head.
Would be good to have you along.
Adam