That’s ok then,
Made me and George( my terrier) jump a bit when it first did it.
Half expected to see the van adrift in my mirrors.

Most 2006 vans and those from around that time will have an AlKo hitch with inbuilt stabiliser pads fitted, though, surprisingly, it was a cost option 'til 2010ish. If the van hasn't got an anti sway hitch and has the basic grey metal trailer type hitch, then that needs a greased towball. Otherwise, if it has a hitch with anti-sway pads the towball has to be totally smooth, shiny and clean to allow the pads to grip and do what they're designed for. I was going to write squeaky clean but in view of the original question I thought better of it.

Next newbie question,
Got a site booked for the bank hols,:-)
The van is now hooked up to mains power,
With the built in charger,I’m guessing it will just maintain the batt charge?
No risk of overcharging or battery damage?
If I choose to not hook up on site,what sort of duration can I expect from a 100ah batt.
Just lights and water pump.
I’ll need to use the motor mover to hitch up at home but that won’t be excessive.(few minutes)
I’ve no split charge on tow vehicle as yet..

If you don't have a hook up you'll have to run the fridge on gas when pitched, so light it beforehand to make sure it works and that you know how. The fridge won't have the benefit of running during the journey so make sure it's well chilled down on either gas or mains electric before departure. And make sure you have enough gas to run the fridge, hobs and maybe heating if it gets chilly.