The maximum towing capacity of your car should be 1650 kgs but the recommended braked towing limit of your car should be no more than 85% of your vehicles kerb weight.
How else can you find out the weights as its a Motability car so i don't have the V5... and i didn't pass my test until 2003 so i know i will have to take a test.
Look at the plate on the car, usually in the drivers door frame. You will see 4 weights
1 gross Train Weight
2 Car max fully loaded weight
3 max weight for front axle
4 Max weight for rear axle.
If you subtract 2 from 1 that will be your max braked trailer towing weight.
As Navver says, look at the VIN plate for the towing capacity.
You won't have to take a test. On a B licence gained after 1.1.97, you can legally tow, as long as the gross plated weight of the car+caravan combination does not exceed 3500kg. The gross weight of the car is figure 2 on the VIN plate; the gross (fully laden) weight of the caravan should be shown on a plate on the outside of the caravan, usually near the door. These days, for modern caravans, it's known as the MTPLM (maximum technically permitted laden mass).