no-one has said this, so I'm gonna:
Make sure it's a diesel ! Pref TD4.
I've the TD4 auto and towed quite happily with it, just need to drive as carefully as you would any car when towing. MHM is right on the button about the additional oil cooler for the auto box though, depending on how big your caravan is and where you're towing it, think it was called "air blast cooler" but not sure