[Gustomaximus]

Then I'd suggest ensure you have some savings together to cover a 'just in case' prolonged search then talk to your employer that you need a better notice period as you keen for something new. Pitch it as this gives to time to find the right job rather than rush off. They might be reasonable. You might even end up with a counter offer that makes you want to stay.

If they won't change, quit on the spot. Then you've got 3 months to find a job.

Edit: Added the pitch it as.