Everyone will have their own opinion on this subject matter. Here are some main points-:

Private schooling is a must for expats. Their are quite a number of options but student slots are few. You must act quick if you are relocating to Qatar.

Most schools follow the British system. You also have the American system available too at the main American school and a few others. IB for older kids is also available in a couple of schools.

I can't really compare to the UK etc... as did my own schooling in the Gulf and my daughter has only been to school in Doha.
No school in my opinion has managed to secure all aspects that form a really good school. E.g student focus, addressing and dealing with improving a child in a certain subject, maintaining a healthy social environment etc.... You come across individual teachers that are fantastic and working with their heart so to speak. It's their effort not the school as a whole.

Hope this helps a little