then after completion of your vacation you should be back immediately with your company.

If your plan is to take vacation and resign (or not to come back) to the company then you'll have to stay out of Qatar for two years. You can not come back with another company.

If you resign and get a NOC from actual employer then you can come back with another company immediately.

Those are the only options: either you leave and wait for 2 yrs or get a NOC and come back immediately.

Regards!!