Firstly unless they've changed lately, I don't think that Oxford offer aeronautical Engineering - if you're an Oxbridge snob I believe that Cambridge do, but if planning an aerospace career you'd be better off at one of the big-name aerospace engineering universities such as Imperial, Glasgow, Southampton, Sheffield...
Secondly, I'd suggest you try these:-
"The new science of strong materials", by JE Gordon
"Flight without formulae", by AC Kermode.
You could also do worse than try the technical textbook used for PPL training - that will give you an overview of a lot of subjects from a point that you can discuss. There are several such books, personally I prefer Jeremy Pratt's as the most readable.
G