Internal water tank, standard fit or optional?

I'm toying with the idea of buying a 2012 or even 2013.

Do they all come with internal water tanks? I'm possibly swaying to a 5 or 6 berth T/A Sterling or Swift....especially the 2013 SE's

Do most/all vans now come with 13 pin or are there still some 7N & 7S's about....13 would be favorite

Does anyone have any experience/view with Cranham Caravans in Essex. Good customer service, good prices/deals etc? I am willing to travel a few 100 miles for a good deal though.