notice period

Hello Maria.

You can check the length of your notice here:
http://www.jobat.be/fr/articles/calculez-votre-delai-de-preavis/

Good luck!
Kind regards,
Alison

There are standard, commonly used, notice periods which you may be able to find online but the bottom line is that YOUR notice period is the time detailed in your contract.
It's also worth considering that there is no reason for your employer to absolutely insist that you work your full period of notice - they may, for example, have been looking for a way to downsize and be happy to let you go.
All you can do is discuss it with your employer and see how they feel. So long as they do not owe you money there is not much that they can do if you just up and leave the country.