The car weight that you need is the Kerb weight rather than the maximum towing weight.
You then need the caravan's ALW (Actual Laden Weight), which is the caravan's unladen weight + whatever payload that you add yourself (keeping this within the manufacturer's MTPLM (Maximum Technical Permissible Laden Mass)). The MTPLM will be in the caravan handbook and possibly on a plate next to the door.
The caravan's ALW shouldn't exceed 85% of the car's Kerb weight. The car's handbook should also show the maximum train weight which is the total weight of the fully laden car + fully laden caravan. The train weight shouldn't be exceeded. Also the maximum towing weight shouldn't be exceeded.
I don't know what the kerb weight of your actual car is, but I've found the weight for a 306 1.9TD on the web and it's quoted as 1080kgs. Therefore applying the 85% rule, means that your caravan ALW shouldn't exceed 918kgs. Given the caravan weight of 727kgs as you've quoted, this will allow you to carry 191kgs of your own contents. So you'll need to be careful if you want to carry an awning, gas bottles, battery, spare wheel etc + your own possessions, food sleeping bags etc. If the kerb weight is less than 1080kgs, then your allowance will be less.
I hope that you can follow this. Provided that you keep your allowance as low as possible then you should be OK.