Tom, unless you have a reason to go to AUH, I would do DXB instead for several reasons. First, immigration is easier and quicker. They are less likely to hassle you. Second, AUH is a dump. It looks like it was built in the 1960's and for all I know it was. Third, the lounge isnt as good. Finally, you have two flights a day instead of only one and the AUH continues on to MCT. So if you have a delay in MCT then you will be delayed as well. The day LHR-DXB flight is actually a really night flight, especially if you happen to get a 747.