If you go for the night ferry (and this isn't a cheap as possible trip) then I'd book a cabin. There might be some spots to sleep but you'll struggle to find somewhere comfy and quiet. Lots of other people will be looking for the same as you so if you're not the first on the ferry you're competing for a limited resource!
With a cabin you will have your own bed and the ability to close turn the lights off, plus privacy and (hopefully) quiet. Possibly even a shower which could be good if the weather is grotty on the trip down from London.
If you're looking to save money then don't get a cabin, but you shouldn't expect to get a good night's sleep.
Bike in the car deck and can normally be locked to something, but better to take your panniers up, if only because you're not allowed back down during sailing if you forget something.
Also second getting a cabin if possible. I did Portsmouth - St Malo in a chair and it was shit.
If you go for the night ferry (and this isn't a cheap as possible trip) then I'd book a cabin. There might be some spots to sleep but you'll struggle to find somewhere comfy and quiet. Lots of other people will be looking for the same as you so if you're not the first on the ferry you're competing for a limited resource!
With a cabin you will have your own bed and the ability to close turn the lights off, plus privacy and (hopefully) quiet. Possibly even a shower which could be good if the weather is grotty on the trip down from London.
If you're looking to save money then don't get a cabin, but you shouldn't expect to get a good night's sleep.