Your Altea weighs 1300kg laden. The Golf is 1389kg making it a 94% match.
this is pasted directly from whattowcar for your outfit:
The match between car and caravan is plausible in accordance with a mix of European standards. However, according to the British Towing Code the percentage (loaded caravan / kerbweight tow car) is 94%.
The towing performances of this Volkswagen with your Adria are good (performance index = 89 km/h or 55 mph).
You may expect more than adequate performances from this outfit. On flat roads you can come along provided you've selected the right gear, in which case top gear is applicable under favourable circumstances.
On motorway inclines you will be able to come along provided you've selected the right gear. On steep roads you have more than sufficient power to keep going. On hill starts there will be more than enough power to get going, provided the wheels have traction.
Andrew (Maesteg)