There are no difficulties on the way. If you leave Doha just after Fajr, you may be able to get Juma prayers in Riyadh. It may take you around 6 hours to get to Riyadh. If you need any further guidance you may call me at 44810951 around 6 PM today or tomorrow as I have traveled several times on the Riyadh-Makkah-Medinah-Qassim-Riyadh route. Ismail