Hi Kim,
Either the caravan has a 13pin socket or the car has the 13pin socket. Does your caravan have 2 x 7pin sockets (Grey & Black)?. You need to look at the car socket and count the total number of pins/holes in the socket.
From a good caravan accessory shop you can get an adaptor plug, but this will only give you the legal road lights (side, brake indicators, hazard and fog lights). It will not work the fridge or caravan leisure battery or any other internal 12 volt on the caravan. But it would let you get away on Saturday.
Longer term and you will have to either change the plug(s) on the car or van. Since you say it is a new Galaxy I would assume that it has been fitted with the new 13 pin socket.
If you are quite good on the electrics you will probably find it easier to change the caravan socket(s) to the 13pin socket.
You get a 2 metre length of 13 core cable,a 13 pin socket and and a 13 pin jointing box, and connect up the appropiate wires