My recommendation is to take an all inclusive tour that includes pick-up and drop off from/to Doha. There are some options available i.e. half day, full day or overnight package and the later two include include meals. You can contact some established operators like Regency Travels (http://www.regencyinbound.com/contactus.html) or Qatar International Adventures (http://www.qia-qatar.com/content/qatar-desert-safari). There might be others as well but I am only aware of these two.