I'm sure Parkdene have plenty of shower and toilet blocks. The least husband can let you do is choose whereabouts on the site your pitch is, that will be reassuring.
Parkdene are really good resorts, giving value for money.
However I would be livid if my husband had decided off the top of his head what type of holiday we'll be having AND had booked it, never mind tents.
What you must do is have a practice run with the tent. If your garden is big enough, try it there (that could be fun, you could have a barbecue and sleep in the tent), or go somewhere secluded away from home and put the tent up there. He would feel a right idiot if he got to the site and found bits missing or wasn't sure how to put it all together securely.
You might enjoy it, plenty of people do, but please don't let him get away with taking fairly big decisions on his own in future.
How do the children feel about it?
I've never camped, didn't fancy it but prompted by this thread I have looked at some superior campsites (with good shower blocks nearby), and tents, and think I might actually have enjoyed it in the right place.
My children would certainly have had a good time at Parkdene, we stayed at a couple of places (one in Cornwall we went to twice), very like the one you are going to but owned by someone else. However we stayed in a chalet each time.
I've also done Center Parcs where the accommodation is lovely but it is expensive for a family, practically everything is 'extra' and the restaurants/cafes are pricey.