depends on the weight of the caravan and the towing capacity of the car, it should be in the manual that came with the car and the weight of the van should be on a plate somewhere, I would have thought the astra is a bit small though
If you enter your details into the calculator to the left of this page http://www.whattowcar.com/ you will get a very good guide to how your car will perform with the 'van behind.