What are your other choices?
If you like the sound of General Engineering then I would advise you to go for that rather than specialise, if you haven't made your mind up yet then you might as well give yourself the extra couple years to decide if you can.
Don't think too much about your career destination yet. As a PhD student with an aerospace degree that's working with a research group with a lot of experience in the Middle East (basically the trifecta for your career destinations lol), you won't really know if academia is right for you until the late stages of your degree, some people won't even know until after they've started their PhD. Working for NASA as a non-US citizen requires an extremely good CV and knowing the right people (I think these kind of people would be around at UCL, I don't think so at Durham), working at SpaceX as a non-US citizen is impossible, ESA should be ok and there are a good deal of Satellite production companies in the UK, alongside universities that are involved in the Satellite industry. For working in the Middle East, it's not as great or easy as it sounds, they're rejecting a lot of visa applications now and the feuds between some of the countries is really impacting the opportunities. Money is good, but the bar for entry is increasing too.
I wouldn't worry too much about the spend per student, looking quickly at the guardian mech eng tables, Swansea that has very up to date facilities is rated 4/10.
Can't speak about the population thing.
5 hours away is pretty far, not just from a "pop home every few weekends" point of view, but also generally. I wouldn't say Durham is in the middle of nowhere, but it's pretty far out the way.