It depends on how do you live your life.
A bed space in a shared accommodation may cost QR1000-QR1500. If you want your own then nothing less than QR 2500 to 3500. Public transportation is not good so you need to have your own car or company cab.

Food expenses for single would be QR500 to QR700. If you are party animal then add extra...

If you are not British national then this is the standard of salary for a 1 year experienced.