First Time Tower

We picked the van up this morning from storage where the company we purchased it from kindly delivered it.  After checking everything 5 times we eventually set off home to give it a clean in readiness for our firts outing on Sunday.  Having never towed before I wasn't sure what to expect.  The initial tow away from its pitch at the storage facility was very smooth and felt as though I had nothing behind me.  After joing the A road immediately from site things started to feel a lot different.  Everything felt great moving through the gears upto about 40-50mph when I started to really notice I was towing something.  It almost felt like it was pushing and then pulling on the car even when I was travelling at a steady 40-50mph.  I must admit it wasn't at all what I was expecting as I thought our set up would be more than capable of towing the van.  We had zero weight in the van other than an aquar roll, waste master and 2 gas bottles in the front.  Is this a normal sensation or have I omitted to do something during set up that might help?  The van is a Charisma 560 and weighs approx 1200 unladen.  The car is a Ford Kuga Titanium 2.0D.  Any advice before we set off on Sunday would be great.  Thanks