Van's aren't too bad to drive. But they do take a bit of getting used to.
A few tips are;
Vans are wider and you have no side windows, at some angled t junctions you can end up no being able to see both ways if you pull up at the wrong angle. Try to pull up square to the road you're pulling out into.
When going round tight junctions make sure you allow for the length of the vehicle, it's fairly easy to end up catching curbs with your rear wheels otherwise.
Make sure you watch both of your mirrors. Idiots who drive too close will often only be visible in one mirror (and then only just). Make sure you get the side mirrors correctly adjusted, since you have no rear view mirror you'll be using them a lot more.