Novita's advice should be taken.
Do ensure that the school fee's and any capital charges are paid out by the company. In addition, if you do not want to be out of pocket, make sure the non-refundable and refundable school registration and deposits are included.

For example, Doha College has a Qrs.10,000/- refundable deposit per new student. This is returned without interest when the student leaves the school.

The housing allowance is ok but do keep in mind that some compounds are considerably more than 11K per month. (15k and up) Your house hunt may result in finding one and having to do a little subsidizing. Nevertheless, not getting more than 11k does not have to be the deal breaker.

As for your family budget, it really depends from family to family. Having all school related charges taken care of makes a major difference.... You can definitely live on 19k though... definitely.

To help a little, here is a bit of an idea on what we spend family wise, approxmiate mind you.

Food & beverage - Qrs.7,000
Water & electricity (4 bed house) - Qrs.1,200 in summer months and around Qrs.800/900 in winter months.
Kids classes out of school for one - Qrs. 900

Your car allowance is fine and you will easily obtain a car on that allowance. You will probably procure a second car for your wife via bank installments so this will be a monthly expense.

Hope this helps. Your offer is good though, comfortable enough.