There are many expat schools here in Doha and really good ones.
There are waiting lists though and before you accept any contract here, make sure you have the schools paid for by the company. They are too expensive to pay for yourself.
Also have accommodation included in your contract.
Most popular British schools. DESS. Doha college.
Park house( my son when there) compass and Sherboure schools all have British curriculum and the most sort after.
American curriculum is Qatar academy, the American school and English international school.
Please check before you come whether they have places for your sons age.
There are lots of other schools springing up and you could try any of them, but the ones just mentioned are most popular.